InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
If `I(m,n)=int_0^1x^(m-1)(1-x)^(n-1)dx`, then |
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Answer» `I(m,n)=int_0^1 x^(m-1)(1-x)^(n-1) dx` `=int_oo^0 1/(1+y)^(m-1)*(y/(1+y))^(n-1)*(1+y)^2dy` `=int_oo^0 y^(n-1)/(1+y)^(m+n-2)` `=int_0^oo y^(n-1)/(1+y)^(m+n)dy` `=int_0^oo x^(n-1)/(1+y)^(m+n)` option c is correct. |
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| 2. |
Integrate 1+Tanx tan(x+theta) dx |
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Answer» ∫ \(\frac{1+tan\,x\,.\,tan(x+\theta)}{[tan(x+\theta)-tan\,x]}\) (tan(x+θ) - tan x)dx = ∫ \(\frac1{tan\,\theta}\) [tan(x+θ) - tan x] . dx = \(\frac1{tan\,\theta}\) ∫ tan(x+θ)dx - ∫ tan x . dx = \(\frac1{tan\,\theta}\) [-log cos(x+θ)1] + [log |cos x|] + c = \(\frac1{tan\,\theta}\) log |\(\frac{cos\,x}{cos(x+\theta)}\)| + c = cot θ log |\(\frac{cos\,x}{cos(x+\theta)}\)| + c. |
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| 3. |
`int_(0)^(pi//2) cosx e^(sinx) dx` is equal toA. `e+1`B. `e-1`C. `e`D. `-e` |
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Answer» Correct Answer - A Let ` I = int_(0)^(pi//2)cosxe^(sinx)dx` Put `sinx = t rArr cosx dx = dt` As `x rarr 0` then `t rarr 0` and `x rarr pi//2`, then `t rarr 1` `:. I = int_(0)^(t)e^(t)dt = [e^(t)]_(0)^(1)` `= e^(1) - e^(0)=e-1` |
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| 4. |
Evaluate `int_0^(pi/4)(sqrt(tanx)+sqrt(cotx))dx` |
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Answer» `I = int (sqrt(sin x/cos x) + sqrt(cos x/sinx) ) dx` `= int( sinx + cosx)/(sqrtcosx sqrtsinx) dx` `= int(sin x + cos x)/(sqrt(cos x sin x))dx` now , `sin x + cosx ` integral is `- cosx + sinx` now, doing `(sin x - cos x)^2` `= sin^2x + cos^2 x - 2 sinx cos x` `(sin x -cos x)^2 = 1- 2 sinxcosx` `2sinxcos x = 1-(sinx - cosx)^2` `sqrt(sinx cosx) = sqrt((1- (sinx-cosx)^2)/2)` putting it in the equation, we get `= sqrt2 int_0 ^(pi/4) (sinx + cos x)/sqrt(1 - (sinx - cosx)^2)dx` let `sinx - cosx = t` `(cos x + sinx)dx = dt` `x=0 ; t= sin0-cos 0 = -1` `x = pi/4 ; t= 0` now, `sqrt2 int_-1^0 dt/sqrt(1-t^2)` `= sqrt2 [ sin^-1t]_-1^0` `= sqrt2 [ sin^-1 0 - sin^-1(-1)] ` `= sqrt2 [ 0 - (-pi/2)]` `= sqrt2 [xx pi/2 = pi xx sqrt2 /2` `= pi/sqrt2` Answer |
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| 5. |
Evaluate the following integral: `int_0^1(sqrt(tan^(-1)x))/(1+x^2)dx` |
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Answer» let `y= tan^-1 x` `dy/dx = 1/(1+x^2)` when `x=0, y=0` `x=1, y= pi/4` `int_0^(pi/4) sqrt y dy` `2/3[y^(3/2)]_0^(pi/4)` `2/3(pi/4)^(3/2)` `= 2/3 xx 1/4^(2/3) xx (pi)^(3/2)` `= 2/3 xx 1/8 xx (pi)^(3/2)` `= (pi)^(3/2)/12` Answer |
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| 6. |
By using the properties of definite integrals, evaluate the integrals`int_0^(2pi)cos^5x dx` |
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Answer» Let `I = int_0^(2pi) cos^5x dx` We know, `int_0^(2a) f(x) dx= 2 int_0^(a) f(x) dx` when `f(2a-x) dx = f(x)` Here, `cos^5(2pi-x) = cos^5x` `:. I = 2 int_0^pi cos^5x dx` Now, `int_0^(a) f(x) dx=0` when `f(a-x) dx = -f(x)` Here, `cos^5(pi-x) = - cos^5x` `:. I = 2 int_0^pi cos^5x dx = 2*0 = 0` `:. int_0^(2pi) cos^5x dx = 0.` |
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| 7. |
For any integer `n`, the integral `int_0^pie^(cosx)cos^3(2n+1)xdx` has the value |
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Answer» `I = int_(0)^pi e^cosx cos^3(2n+1)x dx` We know, ` int_(0)^a f(x)dx = int_(0)^a f(a-x)dx ` `:. I = int_(0)^pi e^cos(pi-x )cos^3(2n+1)(pi-x) dx` `=> I = int_(0)^pi e^cos x cos^3[(2n+1)pi - (2n+1)x] dx` `=> I = int_(0)^pi e^cos x cos^3[2npi+pi -(2n+1)x]dx` `=>I = int_(0)^pi e^cos x cos^3[pi -(2n+1)x]dx` `=> I = - int_(0)^pi e^cosx cos^3(2n+1)x dx` `=> I = -I` `=>2I = 0=> I = 0` `:. int_(0)^pi e^cosx cos^3(2n+1)x dx = 0` |
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| 8. |
The integral `int_0^pisqrt(1+4sin^2(x/2)-4sin(x/2)dx)`equal(1) `pi-4`(2) `(2pi)/3-4-4sqrt(3)`(3) `4""sqrt(3)-4`(4) `4""sqrt(3)-4-pi/3` |
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Answer» `i_1 = int_0^pi sqrt(1 + 4sin^2 x/2 - 4sin x/2 )dx` `= int_0^pi sqrt((1)^2 + (2sin (x/2))^2 - 2 xx1xx 2sin(x/2))dx` `= int_0^pi sqrt((1-2sin(x/2))^2) dx` `= int_0^pi | 1- 2sin (x/2)|dx` `sin (x/2)= 1/2` `x/2 = pi/6` `x= pi/3` `int_0^(pi/3) (1- 2sin(x/2) dx + int_(pi/3)^pi ( 2 sin(x/2)-1) dx` `= (x+4cos(x/2))| + (-4cos(x/2) - x)|_(pi/3)^pi` `=[(pi/3 + 4cos (pi/6) ) - (0+4coso) + [(-4cos(pi/2) - pi)- (-4cos(pi/6)]` `= [pi/3 + 4 xx sqrt3/2 - 4] + [ - pi + 4 sqrt 3/2+ pi/3]` `= pi/3 + 4 xx sqrt3/2 - 4 - pi+ 4 sqrt3/2 + pi/3` `= 4 sqrt3 - 4 - pi/3` Answer |
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| 9. |
`int e^(tan theta)(sec theta- sin theta) d theta` is equal to: (A) `-e^(tantheta) sintheta+c` (B) `e^(tantheta) sintheta+c` (C) `-e^(tantheta) sectheta+c` (D) `e^(tantheta) costheta+c` |
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Answer» `e^(tantheta)sintheta=e^tantheta sec^2thetasintheta+e^tantheta*costheta` `e^tantheta*costheta=e^tantheta sec^2theta*costheta-e^tantheta*sintheta` `=e^tantheta(sectheta-sinntheta)`. |
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| 10. |
∫sin6x/cos8x dx = .......... |
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Answer» tan7x/7 + C |
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| 11. |
`int1/(cosx+sqrt(3)sinx)` dx equals |
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Answer» `int(dx)/(cosx+sqrt3sinx)` `int(sec^2x/2)/(1-tan^2x/2+sqrt3*2tanx/2` `int(sec^2x/2)/(1-tan^2(x/2)+2sqrt3tan(x/2)` Let `tan(x/2)=t` `1/2sec^2(x/2)dx=dt` `int(2dt)/(1-t^2+2sqrt3t)` `int(-2dt)/(t^2-2sqrt3-1)` `-2int(dt)/(t-sqrt3)^2` Let `t-sqrt3=u` `dt=du` `-2int(du)/(u^2-2^2` `-1/2ln((t-sqrt3-2)/(t-sqrt3+2))+c` `-1/2ln|(tan(x/2)-2-sqrt3)/(tan(x/2)+2-sqrt3)|+c`. |
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| 12. |
Integrate the functions`1/(cos^2x(1-tanx)^2)` |
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Answer» We can write the given expression as, `sec^2x/(1-tanx)^2` Let `1 - tanx = t` Then, `-sec^2.dx = dt` So, `intsec^2x/(1-tanx)^2dx` becomes `int-1/t^2dt` `=1/t+c` Putting value of `t = 1 - tanx`, our answer becomes,`= 1/(1-tan x) +c` |
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| 13. |
Class 12 Maths MCQ Questions of Integrals with Answers? |
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Answer» To help the students in their preparations, Class 12 Maths MCQ Questions of Integrals with Answers were created by subject specialists as per exam pattern and syllabus. The ideas of integrals are given in an exhaustive and straightforward manner. These Important MCQ Questions are exceptionally straightforward and can without much of a stretch help students in learning the interaction of problem-solving. As per the new syllabus, Integration Important Multiple Choice Questions for Class 12 gives you the most recent Questions and solutions. To help you better, students can clarify every one of their questions about every part by practicing these significant Questions and careful clarifications given by our specialists. These Questions will assist students with preparation for the tests. The chapter-wise strategy for planning for your board assessment offers you Integration Important MCQ Questions for Class 12. Practice MCQ Question for Class 12 Maths chapter-wise 1. ∫ 1+sinx/1+cosx . ex dx is equal to (a) ex tan(x/2)+k 2. \(\int\frac{2^x}{\sqrt{1-4^x}}dx\) = K sin-1(2x)+C, then K is equal to (a) ln2 3. If \(\int\frac{2^{1/x}}{x^2}dx=\) k.21/x+C, then k is equal to (a) -1/loge2 4. \(\int\frac{1}{sin^2xcos^2x}dx\) is equal to (a) sin2 x – cos2 x + C 5. \(\int\frac{cos2x-cos2\theta}{cosx-cos\theta}dx\) is equal to (a) 2(sin x + x cos θ) + C 6. ∫cot2x dx equals to (a) cot x – x + C 7. \(\int\frac{sinx+cosx}{\sqrt{1+sin2x}}dx,\frac{3\pi}{4}<x<\frac{7\pi}{4}\) is equal to (a) log |sin x + cos x| 8. If ∫ sec2(7 – 4x)dx = a tan (7 – 4x) + C, then value of a is (a) 7 9. The value of X for which \(\int\frac{4x^3+\lambda4^x}{4^x+x^4}dx=log|4^x+x^4|is\) (a) 1 10. If \(\int\frac{1}{\sqrt{4-9x^2}}dx=\frac{1}{3}sin^{-1}(ax)+C,\) then value of a is (a) 2 11. \(\int\frac{10x^9+10^xlog_e10}{x^{10}+10^x}dx\) equals (a) 10x -x10 + c 12. \(\int\frac{e^x(1+x)}{cos^2(xe^2)}dx \) is equals to (a) -cot (xex) + c 13. If \(\int\frac{1}{(x^2+4)(x^2+9)}dx=A\,tan^{-1}\frac{x}{2}+B\,tan^{-1}(\frac{x}{3})\) +C then A-B = (a) 1/6 14. The value of \(\int\frac{e^x(x^2tan^{-1}x+tan^{-1}x+1)}{x^2+1}\) dx is equal to (a) extan-1x+C 15. If ∫ dx/[(x+2)(x2+1)] = a log |1 + x2| + b tan–1x + (1/5) log |x + 2| + C, then (a) a = -1/10, b = -2/5 16. \(\int x^2e^{x^3}\) dx equals (a) 1/3 ex^3+C 17. ∫ex sec x (1 + tan x) dx equals (a) ex cos x + c 18. ∫tan-1 √x dx is equal to (a) (x + 1)tan-1 √x – √x + c 19. ∫ex(cosx−sinx)dx is equal to (a) ex cosx + C 20. If a is such that \(\int_0^axdx\) ≤ a + 4, then (a) 0 ≤ a ≤ 4 Answer: 1. Answer: (a) ex tan(x/2)+k Explanation: \(\int\frac{1+sin\,x}{1+cos\,x}.e^xdx\) Use \(cos\,x=\frac{1-tan^2(x/2)}{1+tan^2(x/2)},sin\,x=\frac{2tan(x/2)}{1+tan^2(x/2)}\) The integral becomes \(=\int\frac{1+tan^2(x/2)+2\,tan(x/2)}{1+tan^2(x/2)+1-tan^2(x/2)}.e^xdx\) \(=\int\frac{sec^2(x/2)+2\,tan(x/2)}2.e^xdx\) \(=\int\left[\frac12sec^2(x/2)+tan(x/2)\right]e^xdx\) If we take tan (x/2) = f(x), the equation takes the form \(\int e^x\) [f(x) + f'(x)]dx \(=e^x\) f(x) + k \(=e^x\) tan (x/2) + k 2. Answer: (d) 1/ln2 Explanation: \(I=\int\frac{2^x}{\sqrt{1-4^x}}dx\) Let \(2^x\) = z \(\Rightarrow\) \(2^x\) log 2dx = dz \(\Rightarrow\) \(I=\int\cfrac{\frac1{log\,2}}{\sqrt{1-z^2}}dz\) \(=\frac1{log\,2}.sin^{-1}z+c\) \(=\frac1{log\,2}.sin^{-1}(e^x)+c\) \(=k\,sin^{-1}(2^x)+c\) then k \(=\frac1{log\,2}.\) 3. Answer: (a) -1/loge2 Explanation: \(I=\int\frac{2^{\frac1x}}{x^2}dx=k.2^{\frac1x}+C\;\;...(1)\) Let \(\frac1x\) = t \(\Rightarrow\) \(\frac{-1}{x^2}dx=dt\) \(\Rightarrow\) \(\frac{dx}{x^2}\) = -dt Put \(\frac1x\) = t and \(\frac{dx}{x^2}\) = -dt ....in LHS of equation (1) we get \(I=-\int2^t.dt\) \(=-\frac{2^t}{In\,2}+C\) \(=-\frac{2^{\frac1x}}{In\,2}+C\;\;...(2)\) Comparing of RHS of equation (1) with equation (2) we get \(k=-\frac1{In\,2}\) \(\therefore\) \(k=-\frac1{log_e\,2}\) 4. Answer: (d) tan x – cot x + C Explanation: \(\int\frac1{sin^2x\,cos^2x}dx\) \(=\int\frac{sin^2x+cos^2x}{sin^2x\,cos^2x}dx\) \(=\int(sec^2x+cosec^2x)dx\) = tan x - cot x + C 5. Answer: (a) 2(sin x + x cos θ) + C Explanation: as \(\int\frac{2(cos^2x-cos^2\theta)}{cos\,x-cos\,\theta}dx,\) using cos 2x = 2 \(cos^2x\) - 1 = 2 \(\int(cos\,x+cos\,\theta)dx\) = 2 sin x + 2x . cos \(\theta\) + C 6. Answer: (d) -cot x – x + C Explanation: ∫ (cosec2x -1)dx = -cot x – x + C 7. Answer: (d) -x Explanation: as \(\int\frac{sin\,x+cos\,x}{|sin\,x+cos\,x|}dx,\) \(\Rightarrow\) \(-\int\) 1.dx = -x + C {as sin x + cos x < 0 for \(\frac{3\pi}{4}<x<\frac{7\pi}{4}\}\) 8. Answer: (d) −1/4 Explanation: \(\int sec^2(7-4x)dx=\frac{tan(7-4x)}{-4}+C\) \(=-\frac14\) tan (7 - 4x) + C. 9. Answer: (b) loge4 Explanation: \(as\,\frac d{dx}log|4^x+x^4|=\frac1{4^x+x^4}.(4^x.log_e4+4x^3)\) \(=\frac{4x^3+log_e\,4.4^x}{4^x+x^4}\) \(\Rightarrow\lambda=log_e\,4\) 10. Answer: (c) 3/2 Explanation: \(as\int\frac1{\sqrt{4-9x^2}}dx=\frac13\int\frac1{\sqrt{(\frac23)^2-x^2}}dx\) \(=\frac13sin^{-1}(\frac{3x}2)+C\) \(\Rightarrow a=\frac32.\) 11. Answer: (d) log (10x + x10) + c. Explanation: Given: \(\int\frac{(10x^9+10x\,In\,10)dx}{(x^{10}+10^x)}\) To evaluate take \(y=x^{10}+10^x\) \(\frac{dy}{dx}=10x^9+10x\,In\,10\) \(dy=(10x^9+10^x\,In\,10)\;dx\) \(\therefore\) \(I=\int\frac{dy}y=In\,y\) Hence, the correct answer is \(In|(x^{10}+10^x)|\) 12. Answer: (b) tan (xex) + c Explanation: Let \(I=\int\frac{e^x(1+x)}{cos^2(xe^x)}dx\) Put \(x.e^x\) = t Diff.w.r.t..x \(\therefore\) \(x.e^x+e^x.1=\frac{dt}{dx}\) \(\therefore\) \(e^x(1+x)dx=dt\) \(\therefore I=\int\frac{dt}{cos^2t}=\int sec^2tdt\) \(\therefore\) tan t + c \(=tan(x.e^x)+e\) 13. Answer: (a) 1/6 Explanation: Given : \(\therefore\) \(\int\frac1{(x^2+4)(x^2+9)}dx\) \(=A\,tan^{-1}\frac x2+B\,tan^{-1}\frac x3+C\;\;...(i)\) \(\frac1{AB}=\frac1{B-A}(\frac1{A}-\frac1{B})\) \(\therefore\) \(\int\frac1{(x^2+4)(x^2+9)}dx\) \(=\int\frac1{5}(\frac1{x^2+4}-\frac1{x^2+9})dx\) \(=\frac1{5}\left[\frac1{2}tan^{-1}\frac x{2}-\frac1{3}tan^{-1}\frac x{3}\right]+C\) \(=\frac1{10}tan^{-1}\frac x{2}-\frac1{15}tan^{-1}\frac x{3}+C\) Comparing above equation with (i) we get A = \(\frac1{10}\) and B = \(-\frac1{15}\) \(\therefore\) A - B \(=\frac{1}{10}+\frac{1}{15}=\frac{5}{30}=\frac{1}{6}\) 14. Answer: (a) extan-1x+C Explanation: \(\int\frac{e^x(x^2tan^{-1}x+tan^{-1}x+1)}{x^2+1}dx\) \(=\int\frac{e^x[(x^2+1)\,tan^{-1}x)+1]}{x^2+1}dx\) \(=\int e^x(tan^{-1}x+\frac{1}{1+x^2})dx\) \(=e^xtan^{-1}x+c\) Note : \(\int\) \(e^x\)[f(x) + f'(x)] dx = \(e^x\) f(x) + c Here f(x) = \(tan^{-1}x\) 15. Answer: (c) a = -1/10, b = 2/5 Explanation: \(I=\int\frac{dx}{(x+2)(x^2+1)}\) \(\frac{1}{(x+2)(x^2+1)}=\frac A{x+2}+\frac{Bx+C}{x^2+1}\) \(\Rightarrow\) 1 = A(\(x^2\)+1) + (Bx+C) (x+2) \(\Rightarrow\) 1 = (A+B)\(x^2\) + (2B+C)x + A + 2C Comparing coefficients, we get A+B = 0, A+2C = 1, 2B+C = 0 Solving we get A = \(\frac15\), B = \(-\frac15\) and C = \(\frac25\) \(\therefore\) \(\int\frac{dx}{(x+2)(x^2+1)}\) \(=\frac15\int\frac1{x+2}dx+\int\cfrac{-\frac{1}{5}x+\frac{2}{5}}{x^2+1}dx\) \(=\frac15\int\frac1{x+2}dx-\frac1{10}\int\frac{2x}{1+x^2}dx+\frac15\int\frac{2}{1+x^2}dx\) \(=\frac15log|x+2|-\frac1{10}log|1+x^2|\) \(+\frac25tan^{-1}x+C\) \(=a\,log|1+x^2|+b\,tan^{-1}x\) \(+\frac15\,log|x+2|+C\) (given) \(\therefore\) \(a=\frac{-1}{10},b=\frac25\) 16. Answer: (a) 1/3 ex^3+C Explanation: \(\int x^2e^xdx\) Let \(x^3\) = t \(\Rightarrow\) \(3x^2=\frac{dt}{dx}\) \(\Rightarrow dx=dt/3x^2\) \(\therefore\) \(\int x^2\times e^t\times\frac{dt}{3x^2}\) \(=\frac13\int e^tdt\) \(=\frac13e^t+c\) \(=\frac13\times e^{x^3}+c\) 17. Answer: (b) ex sec x + c Explanation: Let \(I=\int e^x\) sec x (1+tan x)dx \(=\int e^x\) (sec x + sec x tan x)dx Also, let sec x = f(x) \(\Rightarrow\) sec x tan x = f'(x) We know that, \(\int e^x\) {f(x) + f'(x)} = \(e^x\) f(x) + C \(\therefore\) I = \(e^x\) sec x + C 18. Answer: (a) (x + 1)tan-1 √x – √x + c Explanation: \(\int tan^{-1}\;\sqrt xdx\) Apply integration by parts \(x\int tan^{-1}\;\sqrt x-\int\frac x{2(1+x)\sqrt x}dx\) \(x\int tan^{-1}\;\sqrt x-\frac12\int\frac{\sqrt x}{1+x}dx\) Let \(\sqrt x\) = t \(\frac{dx}{2\sqrt x}=dt\) dx = 2tdt \(=x\,tan^{-1}\;\sqrt x-\int\frac{t^2}{1+t^2}dt\) \(=x\,tan^{-1}\;\sqrt x-\int dt+\int\frac{1}{1+t^2}dt\) \(x\,tan^{-1}\;\sqrt x-\sqrt x+tan^{-1}\sqrt x+c\) \(=(x-1)tan^{-1}\sqrt x-\sqrt x+c\) 19. Answer: (a) ex cosx + C Explanation: since \(\int e^x\) (f(x) + f'(x))dx = \(e^x\) f(x) + C Here f(x) = cos x, f'(x) = -sin x. So, \(\int e^x\) (cos x - sin x)dx = \(e^x\) cos x + C 20. Answer: (d) -2 ≤ a ≤ 4 Explanation: as \(\int_0^axdx\) ≤ a + 4 Click here to Practice MCQ Question for Integrals Class 12 |
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| 14. |
How can students join Integrals Class 12 Mock Test smoothly? |
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Answer» Now give your CBSE Mathematics exam preparation a boost with Sarthaks eConnect chapter-based CBSE Integrals Class 12 mock test. Mock test of Integrals are provided here. While preparing for class 12 Maths board examination, students should be thorough with all the concepts. If they are clear in the concepts, they should be capable of solving any question. For that, students need rigorous practice. Every question and solution are meticulously created by our subject matter experts. These tests are the closest you can find to that of a real examination. Class 12 Mock test of Integrals covers important concepts such as integrations, definite and indefinite integrals, some properties of definite integrals, fundamental theorem of calculus, and also, the methods of integration such as:
Try our online CBSE class 12 online mock test Integrals and witness a gradual change in your test performance. Attempt more Maths questions to help you gain knowledge and get your goals. These mock test series consist of MCQ Questions for Mathematics. All the Question are framed as per the level of board exam and competitive level too. Click here to start practice: - Class 12 Integrals Mock Test |
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| 15. |
∫e-3x(cosx – 3sinx)dx is equal to |
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Answer» ∫e-3x(cosx – 3sinx) dx ∫ e-3x (-3sinx + cosx) f(x) = sinx,f'(x) = cosx ∫e-3x(-3sinx + cosx) = e-3xsinx + C |
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| 16. |
`int (dx)/(sin(x-a)sin(x-b)`A. `sin(b-a)log|(sin(x-b))/(sin(x-a))|+C`B. `cosec(b-a)log|(sin(x-a))/(sin(x-b))|+C`C. `cosec(b-a)log|(sin(x-b))/(sin(x-a))|+C`D. `sin(b-a)log|(sin(x-a))/(sin(x-b))|+C` |
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Answer» Correct Answer - A `I = int(dx)/(sin(x-a)sin(x-b))` `= (1)/(sin(b-a))int(sin(b-a))/(sin(x-a)sin(x-b))dx` `= (1)/(sin(b-a))int(sin(x-a-x+b))/(sin(x-a)sin(x-b))dx` `= (1)/(sin(b-a))int(sin{(x-a)-(x-b)})/(sin(x-a)sin(x-b))dx` `= (1)/(sin(b-a)) int(sin(x-a)cos(x-b)-cos(x-a)sin(x-b))/(sin(x-a)sin(x-b))dx` `= (1)/(sin(b-a)) int[cot(x-b)-cot(x-a)]dx` `= (1)/(sin(b-a)) [log|sin(x-b)|-log|sin(x-a)|]+C` `= cosec (b-a)log|(sin(x-b))/(sin(x-a))|+C` |
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| 17. |
`inttan^(-1)sqrt(x) dx` is equal toA. `(x+1)tan^(-1) sqrt(x) - sqrt(x) + C`B. `x tan^(-1) sqrt(x) - sqrt(x) + C`C. `sqrt(x) - x tan^(-1) sqrt(x) + C`D. `sqrt(x) - (x+1)tan^(-1)sqrt(x) + C` |
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Answer» Correct Answer - A Let ` I = int1.tan^(-1)sqrt(x) dx` `= tan^(-1) sqrt(x). x - 1/2 int (1)/((1+x)). (2)/(sqrt(x))dx` `= x tan^(-1) sqrt(x) - 1/2 int(2)/(sqrt(x)(1+x))dx` Put `x = t^(2) rArr dx = 2t dt` ` :. I = x tan^(-1) sqrt(x) - int (t)/(t(1+t^(2)))dt` `= x tan^(-1) sqrt(x) - int (t^(2))/(1+t^(2)) dt` `= x tan^(-1) sqrt(x) - int (1-(1)/(1+t^(2))) dt` `= x tan^(-1) sqrt(x) - sqrt(x) + tan^(-1) + C` `= x tan^(-1) sqrt(x) - sqrt(x) + tan^(-1) sqrt(x) + C` ` = (x+1) tan^(-1) sqrt(x) - sqrt(x) + C` |
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| 18. |
`int(x^9)/((4x^2+1)^6) dx` is equal toA. `1/(5x) (4+(1)/(x^(2)))^(-5) + C`B. `1/(5) (4+(1)/(x^(2)))^(-5) + C`C. `1/(10x) (1+4x)^(-5) + C`D. `1/(10)(1/(x^(2))+4)^(-5) + C` |
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Answer» Correct Answer - D Let `I = int (x^(9))/((4x^(2) + 1)) dx = int (x^(9))/(x^(12)(4+1/(x^(2)))^(6))dx` ` = int (dx)/(x^(3)(4+1/x^(2))^(6))` Put `4 + 1/(x^(2)) = t rArr (-2)/(x^(3)) dx = dt` `rArr 1/(x^(3)) dx = - 1/2 dt` `:. I = - (1)/(2) int (dt)/(t^(6)) = - 1/2 [(t^(-6+1))/(-6+1)]+ C` ` = 1/10 [(1)/(t^(5))] + C = 1/10 (4+(1)/(x^(2)))^(-5) + C` |
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| 19. |
Solve`int` `(cos 4x-cos 2x)/(sin 4x- sin 2x)` dx |
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Answer» Let `I = int (cos4-cos2x)/(sin4x-sin2x)dx` `= int (-2sin3xsinx)/(2cos3xsinx) dx` `= int (sin3x)/(cos3x) dx` Let, `cos3x = t => -3sin3xdx = dt` So, our integral becomes, `I = -1/3 int dt/t` `=>I = -1/3 log|cos3x|+c` |
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| 20. |
The area of the region bounded by `y=sinx`, `y=cosx` in the first quadrant is |
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Answer» Area=`int_0^(pi/4) sinxdx+int_(pi/4)^(pi/2) cosxdx` `=(cosx)_0^(pi/4)+(sinx)_(pi/4)^(pi/2)` `=1-cospi/4+sinpi/2-sinpi/4` `1-1/sqrt2+1-1/sqrt2=2-sqrt2` option d is correct. |
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| 21. |
For `x>0`, let `f(x)=int_1^x log_et/(1+t)dt` find the function `f(x)+f(1/x)` and show that `f(e)+f(1/e)=1/2` |
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Answer» `f(x)=int_1^x (log_e^t)/(t+1)dt-(1)` `f(1/x)=int_1^x(log_e^t)/(t+1)dt` `Let t=1/h,dt=-1/h^2dt` `if t=1,h=1 or t=1/x,4=x` `f(1/x)=int_1^x(log_e(1/h))/(1+1/h)(-1/h^2dx)` `f(1/x)=int_1^x(-logh(-1))/(h+1)h dh` `f(1/x)=int_1^x9(log_e^t)/(t(t+1))dt-(2)` Adding 1 and 2 `f(x)+f(1/x)=int_1^x(log_e^t)/(t+1)(1+1/t)dt` `int_1^x(log_e^t)/(t+1)(1+1/t)dt` `int_1^x(log_e^t)/t dt` `logt=v` `1/tdt=dv` `f(x)+f(1/x)=int_0^(logx)vdv` `=[v^2/2]_0^logx` `=(log_e^x)^2/2` `f(e)+f(1/e)=(log_e^e)^2/2=1/2` |
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| 22. |
Evaluate `int_-1^ 1 sin^5xcos^4xdx` |
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Answer» Here,` f(x) = int_-1^1sin^5xcos^4xdx` If we find, `f(-x)`, `f(-x) = int_-1^1sin^5(-x)cos^4(-x)dx` `=int_-1^1-sin^5xcos^4xdx=-int_-1^1sin^5xcos^4xdx` `=-f(x)` that means f(x) is an odd function. We know, `int_-a^af(x)dx = 0`, if f(x) is an odd function. Thus,`int_-1^1sin^5xcos^4xdx = 0` |
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| 23. |
Evaluate `int_(pi/6)^(pi/3)(dx)/(1+sqrt(tanx))` |
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Answer» `I= int_(pi/6)^(pi/3) (dx)/(1 + sqrt(tan x))` `= int_(pi/6)^(pi/3) dx/(1 + sqrt(sinx/cosx))` `I= int _(pi/6)^(pi/3) (sqrt(cosx))/(sqrtcosx + sqrtsinx) dx` `int_a^b f(x) = int_a^b f(a+b-x) dx` `I= int_(pi/6) ^ (pi/3) ( sqrt (cos(pi/3 + pi/6 -x))/(sqrt(cos(pi/3 + pi/6 - x)) + sqrt(sin(pi/3 + pi/6 - x))))dx` `I = int _(pi/6) ^(pi/3) (sqrt sinx)/(sqrt sinx + sqrt cosx ) dx` `2I= int_(pi/6)^(pi/3) ( sqrt cosx + sqrt sinx)/(sqrt sinx + sqrt cosx) dx` `2I= int _(pi/6)^(pi/3) 1.dx` `2I= pi/3 - pi/6= pi/6` `I= pi/12` Answer |
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| 24. |
`int_(-pi/4)^(pi/4)(dx)/(1+cos2x)` isA. `1`B. 2C. 3D. 4 |
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Answer» Correct Answer - A Let `I = int_(-pi//4)^(pi//4)(dx)/(1+cos2x) = int_(-pi//4)^(pi//4)(dx)/(2cos^(2)x)` `= 1/2int_(-pi//4)^(pi//4) sec^(2)xdx = int_(0)^(pi//4) sec^(2)xdx = [tanx]_(0)^(pi//4) = 1` |
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| 25. |
`intx^3/(x+1)dx`is equal to:A. `x+(x^(2))/(2)+(x^(3))/(3)-log|1-x|+C`B. `x+(x^(2))/(2)-(x^(3))/(3)-log|1-x|+C`C. `x-(x^(2))/(2)-(x^(3))/(3)-log|1+x|+C`D. `x-(x^(2))/(2) + (x^(3))/(3) - log|1+x|+C` |
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Answer» Correct Answer - A Let ` I = int(x^(3))/(x+1)dx` `= int (x^(2) - x + 1) - (1)/((x+1))dx` ` = (x^(3))/(3) - (x^(2))/(2) + x - log |x+1|+C` |
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| 26. |
If `intf(x)dx=psi(x)`, then `intx^5f(x^3")"dx`is equal to(1) `1/3x^3psi(x^3)-3intx^3psi(x^3)dx+C`(2) `1/3x^3psi(x^3)-intx^2psi(x^3)dx+C`(3) `1/3x^3psi(x^3)-intx^3psi(x^3)dx+C`(4) `1/3[x^3psi(x^3)-intx^2psi(x^3)dx]+C` |
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Answer» `I= int x^5(f(x^3)) dx` `` let `x^3 = t` `3x^2 dx = dt` `x^2dx = 1/3 dt` now, `int (t *f(t)) dt` `= t int f(t) dt - int (1* int (f(t)) dt) dt` `t psi(**) - int( psi (t)) dt` `x^3 psi(x^3) - 3int x^2 psi (x^3 ) dx` option 2 is correct |
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| 27. |
\(\int\frac{e^x(1 + x)}{cos^2(e^xx)}dx\) is equals to(A) – cot (exx) + C (B) tan (xex) + C (C) tan (ex) + C (D) cot (ex) + C |
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Answer» Answer is (B) = ∫ sec2(xex). ex(1 + x)dx = tan (xex) + C |
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| 28. |
Integrate the function sec2(7 – 4x) |
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Answer» ∫sec2(7 - 4x)dx = \(\frac{tan(7 - 4x)}{-4}\)+ c |
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| 29. |
∫ex (cos x – sin x)dx is equal to(A) ex cos x + C (B) ex sin x + C(C) – ex cos x + C(D) – ex sin x + C |
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Answer» (A) is the correct answer since ∫ex [ f ( x) + f '( x)] dx = ex f ( x) + C . Here f (x) = cosx, f′ (x) = – sin x. |
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| 30. |
Integrate the function sinx sin(cosx) |
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Answer» ∫sinx sin (cosx)dx cosx = t ⇒ – sinx . dx = dt ∫- sin t. dt = cos t + C = cos (cos x) + C |
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| 31. |
Find the integrals of the functions ex(sin x + cos x) |
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Answer» ∫ex (sin x + cosx) dx put f(x) = sin x f’(x) = cos x = ∫ex (f(x) + f’(x)) dx = exf'(x) + C =∫ex (sinx + cosx) dx = ex sin x + C |
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| 32. |
Find the integrals \(\int\frac{2 - 3sinx}{cos^2x}dx\) |
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Answer» ∫(2sec2x – 3secxtanx)dx = 2 tan x – 3 sec x + C |
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| 33. |
Find the integrals ∫(2x – 3cosx + ex)dx |
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Answer» ∫(2x – 3cosx + ex)dx = \(\frac{2x^2}{2} \) + 3sinx + ex = x2 - 3sinx + ex + c |
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| 34. |
Find the integrals ∫sec x(secx + tanx)dx |
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Answer» ∫sec x (secx + tanx)dx = ∫(sec2x+sec x tanx)dx = tanx + secx + C |
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| 35. |
Find the integrals ∫x2(1 - \(\frac{1}{x^2})dx\) |
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Answer» ∫x2(1 - \(\frac{1}{x^2}\))dx = ∫(x2 - 1)dx = \(\frac{x^3}{3}\)- x + C |
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| 36. |
Find the integrals ∫(ax2 + bx+c)dx |
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Answer» ∫(ax2 + bx + c)dx = a\(\frac{x^3}{3}\)+ b\(\frac{x^2}{2} + cx\) + d |
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| 37. |
Evaluate `int_0^1(tan^(-1)x)/(1+x^2)dx` |
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Answer» let `tan^-1 x = t` then `dx/(1+x^2) = dt` when `x=0, t=tan^-1 0 = 0` when `x=1, t=tan^-1 1 = pi/4` putting it in the given equation I `= int_0^(pi/4) t dt ` `= [t^2/2]= 1/2 [t^2]` `= 1/2 *(pi/4)^2 - 0)` `= pi^2/32` answer |
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| 38. |
Find the following integrals:(i) `int(sinx+cosx)dx` (ii) `intcosecx(cosecx+cosx)dx`(iii) `int(1-sinx)/(cos^2x)dx` |
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Answer» (i) `int(sinx+cosx)dx = -cosx+sinx+c` (ii)`int cosecx(cosecx+cotx)dx` `=int cosec^2x dx+ int cosecxcotxdx` `= - cotx+(-cosecx)+c` `= - cotx-cosecx+c` (iii) `int (1-sinx)/cos^2xdx` `= int (1/cos^2x - sinx/cos^2x) dx` `= int sec^2x dx - int tanxsecx dx` `= tanx-secx+c` |
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| 39. |
Integrate the functions`e^(3logx)(x^4+1)^(-1)` |
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Answer» I `= int e^(3log x) (x^2 + 1)^-1 dx` `= int e^(log x^3) 1/(x^2+1) dx` `= x^3/(x^4 + 1) dx` let `x^4 + 1 = t` `4x^3 dx = dt` `x^3dx = dt/4` `int (dt/4)/t` `= 1/4 int dt/t` `=1/4 log |t|` `= 1/4 log|x^4+1| + c` answer |
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| 40. |
`int dt/sqrt[3t-2t^2]` |
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Answer» `I = int dt/sqrt(3t-2t^2)` `3t-2t^2 = -(2t^2-2*sqrt2*3/(2sqrt2)t +(3/(2sqrt2))^2-9/8)` `=-(sqrt2t-3/(2sqrt2))^2 + 9/8` `=> I = int dt/(sqrt((3/(2sqrt2))^2-(sqrt2t-3/(2sqrt2))^2)` Let `sqrt2t-3/(2sqrt2) = x=>sqrt2dt = dx` `:. I = 1/sqrt2 int dx/(sqrt((3/(2sqrt2))^2-x^2` we know, ` int 1/sqrt(a^2-x^2) = sin^-1(x/a)` `:.I = 1/sqrt2sin^-1((2sqrt2x)/3)+c` We have, `sqrt2t-3/sqrt2 = x=>2t-3 = sqrt2x` `:. I = 1/sqrt2sin^-1((2(2t-3))/3)+c` |
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| 41. |
∫ f( x→0,2a)(x) dx = 2∫ f(x→0,a)(x) dx , if f (2a – x) = _______. |
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Answer» Answer is f (x). |
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| 42. |
1. Choose the correct answer from the bracket.∫ex dx = -(e2x + c, e-x + c, e2x + c) 2. Evaluate: ∫ ex sinxdx |
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Answer» 1. ex + c 2. I = ∫ex sinxdx = sinx.ex – ∫cos x.exdx = sin x.ex – (cos x.ex – ∫(- sin x).ex dx) = sinx.ex – cosxex – ∫sinx.exdx = sin x.ex – cos xex – I 2I = sin x.ex – cos xex I = \(\frac{1}{2}\)ex(sinx – cosx) + c. |
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| 43. |
Find the integrals ∫(4e3x + 1)dx |
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Answer» ∫(4e3x + 1)dx = \(\frac{4e^{3x}}{3} + x\) = \(\frac{4}{3}\)e3x + x + C |
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| 44. |
Find the integrals ∫(2x2 + ex)dx |
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Answer» ∫(2x2 + ex)dx = 2 x \(\frac{x^3}{3}\)+ ex + C |
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| 45. |
Find the integrals \(\int\frac{x^3 - x^2 + x - 1}{x - 1}dx\) |
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Answer» \(\int\frac{x^2(x - 1) + 1(x - 1)}{(x - 1)}\) = ∫(x2 + 1)dx = \(\frac{x^3}{3}\)+ x + c |
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| 46. |
Find the integral`int(x^3+5x^2-4)/(x^2)dx` |
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Answer» I=`int(x^3+5x^2-4)/x^2 dx` =`int(x+5-4x^(-2) dx` =`x^2/2+5x-4/x+c` |
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| 47. |
Integrate the functions`(2cosx-3sinx)/(6cosx+4sinx)` |
| Answer» `int(2cosx-3sinx)/(6cosx+9sinx) dx`let 6cosx+9sinx=t(2cosx-3sinx)dx=(dt)/2=`int1/t(dt)/2`=`1/2 log|t|+C`=`1/2 log |6 cosx+4sinx|+C` | |
| 48. |
Integrate the functions`((logx)^2)/x` |
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Answer» Let `I = int (logx)^2/x dx` Let `logx = t => dx/x = dt` Then, `I = int t^2 dt` `=>I = t^3/3+c` `=>I = (logx)^3/3+c.` |
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| 49. |
Integrate the functions`(1-cosx)/(1+cosx)` |
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Answer» We know, `cosx = 2cos^2(x/2) - 1 => 1+cosx = 2cos^2(x/2)` Also, `cosx = 1 - 2sin^2(x/2) => 1-cosx = 2sin^2(x/2)` `:. (1-cosx)/(1+cosx) = (2sin^2(x/2))/(2sin^2(x/2)) = tan^2(x/2).` `:. int (1-cosx)/(1+cosx) dx = int tan^2(x/2)dx` `= int (sec^2(x/2) - 1) dx` `= tan (x/2)/(1/2) - x +c` `:. int (1-cosx)/(1+cosx) dx = 2 tan (x/2) - x+c.` |
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| 50. |
Find the integrals of the functions tan4x |
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Answer» ∫tan4xdx = ∫(sec2x - 1)tan2x.dx = ∫sec2x.tan2x - ∫tan2x.dx = ∫(tanx)2sec2x - ∫(sec2x - 1)dx \(= \frac{tan^3x}{3} - tanx + x + c\) |
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