This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Solve the following differential equations. (dy)/(dx)=(4x+6y+5)/(3y+2x+4) |
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| 2. |
Evaluate the following determinants. [[-6,0,0],[3,-5,7],[2,8,11]] |
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Answer» SOLUTION :`[[-6,0,0],[3,-5,7],[2,8,11]]` `(-6)[[-5,7],[8,11]]`=(-6)(-55-56) (-6)(-111)=666 |
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| 3. |
If the system of equations : 2x+3y-z=0,3x+2y+kz=0,4x+y+z=0 have a set of non-zero integral solutions then,find the smallest positive value of z |
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| 4. |
Pentagons have 5 diagonals, as illustrated below. How many diagonals does the octagon below have? |
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Answer» 8 |
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| 5. |
Draw the graph of y=2cosx + sin2x |
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Answer» Solution :We have `y=f(X) = 2cosx+ sin2x` Clearly, DOMAIN of the function is R. Also `f(x)` is periodic with period `2PI`. So we NEED to draw the graph for the interval for the interval `[0,2pi]`. `f(0) =0` `f(x)=0` `therefore 2cosx+2sincosx=0` `therefore 2cosx(1+sinx)=0` `therefore cosx=0` or `sinx=-1` `therefore x=pi//2` or `x=(3pi)//2` `f^(')(x) = -2sinx+2cosx2x` `=-2(2sin^(2)x+sinx-1)` `=-2(2sinx-1)(sinx+1)` `f^(')(x) =0` `therefore sinx=1//2` or `sinx=-1` `therefore x=pi//6, (5pi)/6` or `x=(3pi)/2` `f(pi//6) = 2cos(pi//6) + sin(pi//3)` `=(3sqrt(3))/2` `f(5pi//6) = 2cos(5pi//6+sin(5pi//3))` `=-3sqrt(3)/2` `f(3pi//2)=0` So important points on graph paper as shown in the following figure. From the points A to B, f(x) increases, from points B to D, f(x) decreases intersecting the x-axis at C, from points D to F, f(x) increases intersecting the x-axis at E. Further `f^('')(x)=-2 cosx-4sin2x` `f^('')(x) =0`at `x=(3pi//2)`, hence it is the point of inflection. Since functions have period `2pi`, the graph of`y=f(x)` for `x in R` is as shown in the following figure.
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| 6. |
Let f(x) be a quadratic expression such that f(x) lt 0 AA x in R . If g(x)f'(x) + f''(x)then for x in R. |
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Answer» `g(x) LT 0` |
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| 7. |
Evaluate the following integrals int x " tanh"^(-1)xdx, |x| lt1 |
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| 8. |
IF bar(a)=2bar(i)+5bar(j)+bar(k),bar(b)=4bar(i)+mbar(j)+nbar(k)are collinear vectors then find m+n |
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| 9. |
Fill in the gaps with correct answer choosing from the brackets.The correct expression is _____.(sin 1^0 > sin1,sin1^0 < sin1, sin1^0 =sin1) |
| Answer» SOLUTION :`SIN1^@ < sin1^@` | |
| 10. |
How many positive integers less than 1000 have the property that the sum of the digits of each such number is divisible by 7 and the number itself is divisible by 3? |
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| 11. |
If A,B and C are angles of a triangle, then the determinant |{:(-1,cosC,cosB),(cosC,-1,cosA),(cosB,cosA,-1):}| is equal to"........." |
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Answer» 0 |
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| 12. |
State true or False .The planes 2x +4y -z + 1 = 0 and x - 2y - 6z + 3 = 0 are perpendicular to each other. |
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| 14. |
Match the points on the curve 2y^2=x+1 with the slope of normals at those points {:("I.",(7,2),"a",-4sqrt2),("II".,(0.1//sqrt2),b,-8),("III.",(1,-1),c,4),("IV.",(3,sqrt2),d,0),("","",e,-2sqrt2):} |
| Answer» Answer :B | |
| 15. |
If Delta_r= |[2r-1, mC_r,1],[m^2-1,2^m,m+1],[m^2+m+1,2^m+1,m+2]|, then sum_(r=0)^m Delta_r= |
| Answer» ANSWER :A | |
| 16. |
The median of 100 observation grouped in classes of equal width is 55 if the median class is 50-60 and the number of observation less than 50 is 45, then frequency of the median class is _______ |
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| 17. |
By vector method prove that the angle in a semi circle is a right angle. |
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| 18. |
If a and b are two unit vectors inclined to X-axis at angles 30^(@) and 120^(@), then |a+b| is equal to |
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Answer» `SQRT((2)/(3))` `implies a.b=0` `:. |a+b|^(2)=a^(2)+b^(2)+2a.b=1+1+0=2` `implies |a+b|=sqrt(2)` |
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| 20. |
Integrate the following functions : intx(4+x)^(1/4)dx |
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| 21. |
For each of the exercises given below, verify that thegiven function (implicit orexplicit) is a solution of the correspondingdifferential equation. (i) xy = ae^(x) + be^(-x) + x^(2) : x (d^(2)y)/(dx^(2)) + 2(dy)/(dx) - xy + x^(2) - 2 = 0 (ii) y = e^(x)(a cos x + b sin x) : (d^(2)y)/(dx^(2))- 2(dy)/(dx) + 2y = 0 (iii) y = x sin 3x : (d^(2)y)/(dx^(2)) + 9y - 6 cos 3x = 0 (iv) x^(2) = 2y^(2) log y : (x^(2) + y^(2)(dy)/(dx) - xy = 0 |
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| 22. |
If each of the obsservationsx_(1) , x_(2) …..x_(n)is o increased by k , is a positive or negative number , then show that the variance ramains unchanged . |
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| 23. |
If A=[{:(1,0,2),(0,2,1),(2,0,3):}]then , prove that A^(3)-6A^(2)+7A+2I=O. |
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| 24. |
Find the number of ways of selecting cricket eleven from 20 players such that at least one of Sachin and Dravid must be excluded |
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| 25. |
The value of int_(-(pi)/(2))^((pi)/(2)) sqrt((1-cos 2x)/(2x)) dxis |
| Answer» Answer :2 | |
| 26. |
Find a vector of magnitude sqrt(51) and makes equal angle with the vectors vec(a)=(1)/(3)(hati-2hatj+2hatk),vec(b)=(1)/(5)(-4hati-3hatk) and vec( c )=hatj. |
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| 27. |
If the coefficients of rth and (r+1)th terms in the expansion of (1+x)^(24) are in the ratio 12 : 13, then r is the root of the quadratic equation |
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Answer» `x^(2) - 5x + 6 = 0` |
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| 28. |
If a=1,+x+x^2... and b=1+y+y^2+...[x|lt1and]y|lt1, then prove that 1-xy+x^2y^2+x^3y^3+....=(ab)/(a+b-1) |
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Answer» Solution :`a=1+x+x^2+...=1/(1-x)IMPLIES(1-x)=1 implies a-1=ax implies=(a-1)/a similarly,y=(B-1)/b` `therefore1+xy+x^2y^2+....=1/(1-xy)=1/((a-1)(b-1))/1-(AB)=(ab)/(ab-(ab-a-b+1))=(ab)/(a+b-1)` |
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| 29. |
If a random variable X has a binomial distribution B (8,1/2) then find X for which the outcome is the most likely. |
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Answer» SOLUTION :GIVEN binomial distribution is B `(8.1/2)` THUS n=8,p=`1/2,q=1/2` We shall find X which is most likely i.e.for which p(x-r) is maximum where r=0,1,2,.......,8 As p=q, the probability is maximum when `^8C_r` is maximum But `^8C_r`,r=0,1,2,....... 8 is maximum when r=4. Thus the most likely OUTCOME is x=4. |
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| 30. |
Find the number of ways of arranging 7 gents and 4 ladies around a circular table if no two ladies wish to sit together. |
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| 31. |
The solution of (x^(2) + 1) (dy)/(dx) + 4xy = (1)/(x^(2) + 1) is |
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| 32. |
Three persons A, B and C, fire at a target in turn starting with A. Their probability of hitting the target are 0.4, 0.3 and 0.2 respectively. The probability of two hits is ………… |
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Answer» 0.024 |
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| 33. |
Find the rank of the following matrices by row reduction method.[[3,-8,5,2],[2,-5,1,4],[-1,2,3,-2]] |
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| 34. |
If Q is the image of the point P(2,3,4)under the reflection in the plane x-2y+5z =6 , then the equation of the line PQ is |
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Answer» `(x-2)/(-1)=(y-3)/2=(z-4)/5` |
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| 35. |
Construct truth tables for the following and indicate which of these are tautologiesp^^(porq)rarr q. |
Answer» SOLUTION :
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| 36. |
Consider the binary operations ** R xx R rarrR and o : RxxR rarrR defined as a**b |a-b| and " a o b " = a, AA a , b in R . Show that ** is commutative but not associative , o is associative but not commutative. Further, show that AA a , b ,c in R , a ** ("b o c")= (a**b) o (a**c) . [If it is so , we say that the operation ** distributes over the operation o] . Does o distribute over ** ? Justify your answer. |
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| 38. |
Form the differential equation representing the given family of curves y= asin(x+b) where a,b are arbitrary constants. |
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| 39. |
If x = alpha, y = beta, z = gamma is the solution, for the system of equations 2x - y + 8z = 13 3x + 4y + 5z = 18 5x - 2y + 7z = 20 then alpha beta + beta gamma + gamma alpha = |
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Answer» 1 |
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| 40. |
The volume of a cube is increasing at the rate of 8 cm^(3) /s. How fast is the surface area increasing when the length of an edge is 12 cm? |
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| 41. |
Find the domains of defination of the following functions: (a) f(x)=sqrt(x^(3)-x^(2)), (b f(x)=sqrt(sin sqrtx) (c) fx)=sqrt(-sin^(2) pix), (d) f(x)=(1)/sqrt(|x|-x|) and g(x)=1/sqrt(x-|x|) (e) f(x)=arc sin (|x|x-3), (f) f(x)=arc cos ""1/(sin x) |
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Answer» (c) `x=0, PM 1, +2,.....; (d) (-oo,0)` (e) `[-4,2] or [2,4]` `(f) x=(2n+1) pi/2 (n=0, pm1, PM2,...)` |
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| 42. |
Prove thatsum_(k=0)^(n) (-1)^(k).""^(3n)C_(k)= (-1)^(n). ""^(3n-1)C_(n) |
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Answer» Solution :Wehave, `S = underset(k = 0)OVERSET(N)sum(-1)^(k) . .^(3n)C_(k) = .^(3n)C_(0) - .^(3n)C_(1) + .^(3n)C_(2) + "……" + (-1)^(n)..^(3n)C_(n)` But `.^(3n)C_(0) = .^(3n-1)C_(0)` `-.^(3n)C_(1) = -.^(3n-1)C_(0) - .^(3n-1)C_(1)` `.^(3n)C_(2) = .^(3n-1)C_(1).^(3n-1)C_(2)` `-.^(3n)C_(3) = -.^(3n-1)C_(2) - .^(3n-1)C_(3)` `{:("......"),("......"):}""{:("......"),("......"):}` `(-1)^(n)..^(3n)C_(n) = (-1)^(n).^(3n-1)C_(n-1)+(-1)^(n).^(3n-1)C_(n)` On adding, we GET `S = (-1)^(n).^(3n-1)C_(n)`. |
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| 43. |
Let X ={x,y} and Y ={u,v}. Write down all the functions that can be defined from X To Y. How many of these are (i) one-one (ii) onto and (iii)one-one and onto ? |
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Answer» Solution :The function from X={x,y} to y ={u,v} are :`f_1 ={(x,u),(y,v)}` `f_2={(x,v),(y,u)}` `f_3 ={(x,4),(y,u)` `f_4={(x,v),(y,v)}` Out of these 4 FUNCTIONS there are :(i) 2 one-one functions (ii) 2 ONTO functions (III) 2 one-one and onto fuction. |
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| 44. |
Consider the unction f(x)=int_(0)^(x)(5ln(1+t^(2))-10t tan^(-1)t+16sint)dt Which is not true for int_(0)^(x)f(t)dt gt? |
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Answer» POSITIVE for all `x in (0,1)` `rArr""f'(x)=5ln(1+x^(2))-10x tan^(-1)x+16 SINX` `rArr""f''(x)=2(8 cos x-5 tan^(-1)x)` `rArr""f''(x)=-2(8sinx+(5)/(1+x^(2)))lt0AAx in (0,1)` So, f''(x) is decreasing `AA x in (0,1)` `rArr""f''(x)gtf''(1)=2(8cos1-(5pi)/(4))` `""gt2(8cos.(pi)/(3)-(5pi)/(4))` `""=2(4-(5pi)/(4))gt0` So, f''(x) is increasing, for `x gt 0 , f'(x)gtf'(0)=0` So, f(x) is increasing, for `x gt0, f(x) gt f(0)=0` So, `int_(0)^(x)f(t)` is positive and increasing. |
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| 45. |
int(x^(2))/((x^(2)+a^(2))(x^(2)+b^(2)))dx |
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Answer» `(1)/((a^(2)-b^(2)))[(1)/(b)tan^(-1)((x)/(b))-(1)/(a)"tan"^(-1)((x)/(a))]+C` |
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| 46. |
The magnitude of the projection of vector (4, 1, 3) and (1, -2, 3) is ……………. |
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Answer» `(15)/(SQRT(14))` |
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| 47. |
Hannah is 5 years younger than Nora , who is x years old, Which of the following is an expression for Hannah's age in 2 years ? |
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Answer» x-3 |
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| 48. |
If f(x) is a function of x such that (1)/((1+x)(1+x^(2)))=(A)/(1+x)+(f(x))/((1+x^(2)) for all x in R then f(x) is |
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Answer» `(1-x)/(2)` |
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| 49. |
Consider the non-empty set consisting of children in a family and a relation R defined as aRb, if a is brother of b. Then, R is |
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Answer» SYMMETRIC but not transitive |
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