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51.

The function `f(x)=(4-x^2)/(4x-x^3)`a)discontinuous at only one pointb) discontinuous exactly at two pointsc)discontinuous exactly at three pointsd) none of these

Answer» `f(x) = (4-x^2)/(4x-x^3 )`
`= (4 -x^2)/(x(4- x^2))`
`f(x) = (4-x^2)/(x(2-x)(2+x))`
`x= 0, 2,-2`
at `x=0,2,-2`
so, f(x) is discontinuous
answer
52.

The function `f(x) =(2x^(2)+7)/(x^(3)+3x^(2)-x-3)` is discontinuous forA. `x=1` onlyB. `x=1, -1` onlyC. `x=1, -1,-3` and other values of xD. `x=1, -1, -3` only

Answer» Correct Answer - D
53.

Determine the value of `k`for which the following function is continuous at `x=3.``f(x)={(x^2-9)/(x-3)` ,`x!=3`and k when `x=3`

Answer» `1) LHL = RHL`
`2) LHL = RHL`= value of f(x)
LHL=`lim_(x->3) (x^2 - 9)/(x-3)`
`x= 3-h`
`:. lim_(h->0) ((3-h)^2 - 9)/((3-h)-3)`
`= lim_(h->0) (9-h^2 - 6h - 9)/((3-h) - 3)`
`= lim_(h->0) (h(h-6))/(-1)`
`= 6`
RHL=`lim_(x->3) (x^2-9)/(x-3)`
`x= 3 + h`
`lim_(h->0) ((3+h)^2 - 9)/(3+h-3)`
`lim_(h->0) (h^2 + 6h)/h`
`lim_(h->0) h + 6 = 6`
LHL=RHL = f(3)
`6= k`
Answer
54.

Are the following functions continuous on the set of real numbers? Justify your answers.f(x) = e

Answer»

Given, f (x) = e

It is a constant function …. [∵ e = 2.71828]

∴ f(x) is continuous on the set of real numbers i.e., x ∈ R.

55.

Are the following functions continuous on the set of real numbers? Justify your answers.f(x) = 7

Answer»

Given, f(x) = 7

It is a constant function.

∴ f(x) is continuous on the set of real numbers i.e., x ∈ R.

56.

Are the following functions continuous on the set of real numbers? Justify your answers.f (x) = log 19

Answer»

Given, f(x) = log 19

Here, log 19 is a constant

∴ f(x) is a constant function

∴ f(x) is continuous on the set of real numbers i.e., x ∈ R.

57.

g(x) = sin (4x - 3)

Answer»

Given, g(x) = sin (4x - 3)

It is a sine function

∴ f(x) is continuous on the set of real numbers i.e., x ∈ R.

58.

Are the following functions continuous on the set of real numbers? Justify your answers.f(x) = 5x

Answer»

Given, f(x) = 5x

It is an exponential function

∴ It is continuous on the set of real numbers i.e., x ∈ R.

59.

Determine the value of constant k so that the function\(f(x) =\begin{cases}\frac{1 - cos\,kx}{x\,sin\,x}, & \quad x \neq 0\\2, & \quad x=0\end{cases}\) is continuous at x = 0f(x) = {(1 - cos kx)/(x sin x), x ≠ 0, 2, x = 0 is continuous at x = 0(A) k = ± 2(B) k = ± 4(C) k = ± 1(D) k = ± 3

Answer»

Correct answer is

(A) k = ± 2

60.

Are the following functions continuous on the set of real numbers? Justify your answers.f(x) = e(5x + 7)

Answer»

Given, f(x) = e(5x + 7)

It is an exponential function

∴ It is continuous on the set of real numbers i.e., x ∈ R.

61.

The function \(f(x) = \frac{log(1 + ax) - log(1 - bx)}{x}\) is not defined at x = 0. The value which should be assigned to f at x = 0 so that it is continuous at x = 0, isf(x) = (log(1 + ax) - log(1 - bx))/(x)(A) a - b(B) a + b(C) log a + log b(D) log a - log b

Answer»

Correct answer is

(B) a + b

62.

Let`f(x)={(1-cos4x)/(x^2a,),ifx0,ifx=0`Determine the value of `a`so that `f(x)`is continuous at `x=0.`

Answer» LHL=`f(0^-)`
`f(x) = (1- cos 4x)/x^2`
`= (2sin^2 2x)/(x^2)`
`=> 2(sin2x)/(2x) *(sin2x)/(2x) *2*2= 8`
`sqrtx/(sqrt(16 +sqrtx) - 4) xx (sqrt(16+ sqrtx))/(sqrt(16 + sqrtx) + 4)`
`=(sqrtx( sqrt(16 + sqrtx) + 4))/(16 + sqrtx - 16)`
`= sqrt(16 + sqrtx) + 4`
`= sqrt16 + 4 = 4 + 4 = 8`
so,`a=8`
Answer
63.

Given the function `f(x)=1/(x+2)`. Find the points of discontinuity of the function `f(f(x))`

Answer» `f(x) = 1/(x+2) `
`x=-2`
`f(f(x)) = 1/((1/(x+2)) + 2)`
`= (x+2)/(2x+5)`
`2x+5= 0`
`x=-5/2`
Answer
64.

For what value of `k`is the function`f(x)={(x^2-1)/(x-1)k,``,x!=1,x=1"c o n t i n u o u sa t"x=1?`

Answer» As `f(x)` is continuous at `x = 1`,
`:. Lim_(x->0) f(x) = f(1).`
`=>Lim_(x->0)(x^2-1)/(x-1) = k`
`=>Lim_(x->0)((x+1)(x-1))/(x-1) = k`
`=>Lim_(x->0)(x+1) = k`
`=> 2 = k`
`:.` For `k = 2`, given function will be continuous at `x = 1`.
65.

Let`f(x)=(log(1+x/a)-log(1-x/b))/x ,x!=0.`Find the value of `f` at `x=0`so that `f`becomes continuous at `x=0`

Answer» `f(x) = (log(1) - log(1))/0 = 0/0`
`f(0) = f(0+h) = f(0-h) `
`l = lim_(x->0) f(x) = lim(x->0) (log(1 + x/a) - log(1-x/b))/x = 0/0`
applying l hospital rule
`l = lim_(x->0) (1/(1+ x/a) *1/a - 1/(1-x/b) (-1/b))/1`
`l = lim_(x->0) ((1/(1+0) *1/a + (1/(1-0) *1/b))/1)`
`l = 1/a + 1/b = (a+b)/(ab)`
so, `f(0) = (a+b)/(ab)`
Answer
66.

If the function `f(x)`defined byf(x)=`(log(1+3x)-"log"(1-2x))/x `, `x!=0` and k , x=0.Find k.

Answer» `f(x) = (log(1+3x) - log(1-2x))/x`
`l = lim_(x->0) (log(1+3x) - log(1-2x))/x`
`l = lim_(x->0) (1/(1+3x) * 3 - 1/(1-2x) (-2))/1`
`l = lim_(x->0) 3/(1+3x) + 2/(1-2x) `
`l = 3/1 + 2/1 = 5`
`f(0) = f(0^-) = f(0^+)`
`k = 5`
Answer
67.

The value of `f(0),`so that the function`f(x)=(sqrt(a^2-a x+x^2)-sqrt(a^2+a x+x^2))/(sqrt(a+x)-sqrt(a-x))`becomes continuous for all `x ,`given by`a^(3/2)`(b) `a^(1/2)`(c) `-a^(1/2)`(d) `-a^(3/2)`A. `-a sqrt(a)`B. `a sqrt(a)`C. `-sqrt(a)`D. `sqrt(a)`

Answer» Correct Answer - C
68.

The function\(f(x) =\begin{cases}3x - 5, & \quad \text{for}\, x<3\\x+1, & \quad \text{for}\, x>3\\c, & \quad \text{for}\, x=3\end{cases}\) is continuous at x = 3, if c is equal tof(x) = {(3x -5), for x < 3, (x + 1), for x > 3, c, for x = 3(A) 4(B) 3(C) 1(D) 2

Answer»

Correct answer is

(A) 4

69.

Determine `f(0)`so that the function `f(x)`defined by`f(x)=((4^x-1)^3)/(sinx/4log(1+(x^2)/3))`becomes continuous at `x=0`

Answer» `lim_(x->0) ((4^x - 1)^3)/(sin(x/4) log(1 + x^2/3))`
`(4^x - 1)^3= (e^(x ln4) - 1)^3 = (1 + xln 4 + (xln4)^2/2 ....-1)^3`
`e^t = 1 + t + t^2/2 + .......`
or `sin(x/4)/(x/4) [ log(1 + x^2/3)] xx x/4 `
or `= [x/3 + (x/3)^2 /2+ ....] xx pi/4`
now, `([xln 4 + (xln4)^2/2]^3)/(x/4* [(x^2/3)^2/2])`
`= (x^3(ln^3 4)/((x/4)(x^2/3)) = 12 (ln4)^3`
`f(0) = 12( ln 4)^3`
Answer
70.

Show that`f(x)=5x-4` , `0< x < 1``f(x)=4x^3-3x` , `1< x

Answer» `x<= 1`
`f(x) = 5x- 4`
`f(1^-) = 5 xx 1 - 4 =1`
`x > 1`
`f(x) = 4x^23 - 3x`
`f(1^+) = 4 xx1 - 3(1) = 1`
`f(1^-) = f(1^+)`
`:. ` continuous
71.

If`f(x)={asinpi/2(x+1), ,xlt=0(tanx-sinx)/(x^3),x >0`is continuous at `x=0`, then a equal(a)`1/2`(b) `1/3`(c) `1/4`(d) `1/6`

Answer» `f(x) = { a sin pi/2 ( x+1) x<= 0 `
`= { (tanx - sin x)/x^3 x>0`
`f(0^-) = (tanx- sin x)/x^3`
`= lim_(x->0) (tan x - sinx)/x^3`
`= lim_(x->0) (sinx[1/cosx - 1])/x^3`
`= lim_(x-0) (1-cos x)/(x^2 cos x)`
`= lim_(x->0) (1-(1- 2sin^2 (x/2)))/(x^2 cos x)`
`= lim_(x->0) (2sin^2 (x/2))/(4 (x/2)^2 cosx)`
`= lim_(x->0) 1/(2cos x) = 1/2`
`a=1/2`
option a is correct
72.

If `f(x)` is continuous at `x=pi/4`, where `f(x)=(1-tanx)/(1-sqrt(2)sin x)`, for `x!= pi/4`, then `f(pi/4)=`A. 2B. `sqrt(2)`C. `2sqrt(2)`D. `(1)/(sqrt(2))`

Answer» Correct Answer - A
73.

If \(f(x) =\begin{cases}\frac{sin\,3x}{sin\,x}, &amp; x \neq 0\\k, &amp; x=0\end{cases}\) is a continuous function, then k =f(x) = {(sin 3x)/(sin x), x ≠ 0, k, x = 0(A) 1(B) 3(C) \(\frac{1}{3}\)(D) 0

Answer»

Correct answer is

(B) 3

74.

At what point on the curve y = x2 , x ∈ [-2, 2] at which the tangent is parallel to x-axis?

Answer»

Y = x2 , a continuous function on [-2, 2] and dierentiable on [-2, 2] f(2) = 4 = f(-2). 

All conditions of Rolles theorem is satised. 

Given 

the tangent is parallel to x-axis. 

f -1 (x) = 2x 

f-1 (c) = 2c

f-1 (c) = 0 ⇒ 2c = 0 ⇒ c = 0 ∈ [-2, 2] 

where c = 0, y = 0 

Therefore (0, 0) is the required point.

75.

If \(f(x) = \begin{cases} \frac{sin(a + 1)x + sin\,x}{x}, &amp; \quad x&lt;0\\ \frac{1}{2}, &amp; \quad x=0\\\frac{x^{3\sqrt{2}+1}}{2}, &amp; \quad x&gt;0 \end{cases}\) is continuous at x = 0, then the value of a isIf f(x) = {(sin(a + 1)x + sin x)/x, x&lt;0, 1/2, x = 0, (x^3√2 + 1)/2, x &gt; 0, then the value of a isA. \(\frac{1}{2}\)B. \(-\frac{1}{2}\)C. \(\frac{3}{2}\)D. \(-\frac{3}{2}\)

Answer»

Correct answer is

(D) \(-\frac{3}{2}\)

76.

Function \(f(x) = \begin{cases} \frac{x^2 - 4x + 3}{x^2 - 1}, &amp; \quad x\neq 1\\ 2, &amp; \quad x=1 \end{cases},\) isf(x) = {(x2 - 4x + 3)/(x2 - 1), x ≠ 1, 2, x = 1 is(A) continuous at x = 1.(B) continuous at x = -1.(C) continuous at x = 1 and x = -1.(D) discontinuous at x = 1.

Answer»

Correct answer is

(D). discontinuous at x = 1.

77.

If the function `f(x) {((1 - cos 4x)/(8x^(2))",",x !=0),(" k,",x = 0):}`is continuous at x = 0 then k = ?A. 16B. 2C. -1D. 1

Answer» Correct Answer - D
78.

If `f(x) ` is continuous at `x=0`, where `f(x)={:{((9^(x)-9^(-x))/(sin x)", for " x!=0),(k", for " x=0):}`, then `k=`A. log 9B. log 81C. 2 log 3D. `(log 9)^(2)`

Answer» Correct Answer - B
79.

If `f(x)` is continuous at `x=0`, where `f(x)=(10^(x)+7^(x)-14^(x)-5^(x))/(1-cos 4x)`, for `x!=0`, then `f(0)=`A. `1/4 (log2)log(5/7)`B. `1/8 (log2) log(5/7)`C. `1/4 (log2) log(7/5)`D. `1/8 (log 2) log (7/5)`

Answer» Correct Answer - B
80.

The function f(x) is condtions at the point x=0 where `f(x)=log(1+kx)/(sinx), "for" x ne 0 ` = 5 for x=0 then value of k isA. 5B. -5C. `1/5`D. `(-1)/(5)`

Answer» Correct Answer - A
81.

If `f(x)` is continuous at `x=0`, where `f(x)=((5^(x)-2^(x))x)/(cos 5x-cos 3x)`, for `x!=0`, then `f(0)=`A. `(-1)/(4) log (2/5)`B. `1/4 log (2/5)`C. `(-1)/(8) log (2/5)`D. `1/8 log (2/5)`

Answer» Correct Answer - D
82.

If `f(x)` is continuous at `x=pi/2`, where `f(x)=(sqrt(2)-sqrt(1+sin x))/(cos^(2)x)`, for `x!= pi/2`, then `f(pi/2)=`A. `4sqrt(2)`B. `2sqrt(2)`C. `(1)/(4sqrt(2))`D. `(1)/(2sqrt(2))`

Answer» Correct Answer - C
83.

If `f(x)` is continuous at `x=0`, where `f(x)=(4^(x)-2^(x+1)+1)/(1-cos x)`, for `x!=0`, then `f(0)=`A. `(2 log2)^(2)`B. `2(log 2)^(2)`C. `(log2)^(2)`D. `((log2)^(2))/(2)`

Answer» Correct Answer - B
84.

If `f(x)` is continuous at `x=a,a>0`, where `f(x)=[(a^x-x^a)/(x^x-a^a)`, for `x!=a`, -1 for x=a, then `a=`A. eB. 2eC. 1D. 0

Answer» Correct Answer - C
85.

Evaluate :`("lim")_(xvec2a^+)(sqrt(x-2a)+sqrt(x)-sqrt(2a))/(x^2-4a^2)`A. `2sqrt(a)`B. 2aC. `(1)/(2sqrt(a))`D. `(1)/(2a)`

Answer» Correct Answer - C
86.

If the function f(x) defined by `f(x)={(x"sin"(1)/(x)",", "for "x ne 0),(k",", "for " x=0):}` is continuous at x = 0, then k is equal to

Answer» Correct Answer - A
87.

If `f(x)` is continuous at `x=a`, where `f(x)=(sin (a+x)+sin(a-x)-2 sin a)/(x sin x)", for " x!=a`, then `f(a)=`A. `2/a (cosa-1)`B. `1/a (cos a-1)`C. `1/a (1-cosa)`D. None of these

Answer» Correct Answer - A
88.

If `f(x)` is continuous at `x=sqrt(2)`, where `f(x)=(sqrt(3+2x)-(sqrt(2)+1))/(x^(2)-2)`, for `x!= sqrt(2)`, then `f(sqrt(2))=`A. `(1)/(2(2+sqrt(2)))`B. `(1)/(sqrt(2)(2+sqrt(2)))`C. `(1)/(2+sqrt(2))`D. `(1)/(2+2sqrt(2))`

Answer» Correct Answer - A
89.

If `f(x)` is continuous at `x=0`, where `f(x)=sin x-cos x`, for `x!=0`, then `f(0)=`A. 2B. 0C. -1D. 1

Answer» Correct Answer - C
90.

If `f(x)` is continuous at `x=0`, where `f(x)=(3-4cos x+cos 2x)/(x^(2))`, for `x!=0`, then `f(0)=`

Answer» Correct Answer - A
91.

The value of k which makes `f(x)={:{(sin(1/x)", for " x!=0),(k", for " x=0):}` continuous at `x=0` is

Answer» Correct Answer - D
92.

If `f(x)` is continuous at `x=0`, where `f(x)=(3-4cos x+cos 2x)/(x^(4))`, for `x!=0`, then `f(0)=`A. `1/4`B. `1/2`C. 8D. 4

Answer» Correct Answer - B
93.

If `f(x)` is continuous at `x=5`, where `f(x)=(sqrt(3+sqrt(4+x))-sqrt(6))/(x-5)`, for `x!=5`, then `f(5)=`A. `(1)/(2sqrt(6))`B. `(1)/(3sqrt(6))`C. `(1)/(12sqrt(6))`D. None of these

Answer» Correct Answer - C
94.

If `f(x)` is continuous at `x=-2`, where `f(x)=(2)/(x+2)+(1)/(x^(2)-2x+4)-(24)/(x^(3)+8)`, for `x!= -2`, then `f(-2)=`A. `(-1)/(4)`B. `1/4`C. `(11)/(12)`D. `(-11)/(12)`

Answer» Correct Answer - D
95.

If `f(x)` is continuous at `x=2`, where `f(x)=((x^(2)-x-2)^(20))/((x^(3)-12x+16)^(10))`, for `x!=2`, then `f(2)=`A. `(3^(20))/(2^(10))`B. `(3^(10))/(2^(20))`C. `(3/2)^(10)`D. `(3/2)^(20)`

Answer» Correct Answer - C
96.

If `f(x)` is contiuous at `x= pi/2`, where `f(x)=(cosec x - sin x)/(pi/2 - x)", for " x != pi/2`, then `f(pi/2)=`A. `1/4`B. `1/2`C. `1/6`D. `1/8`

Answer» Correct Answer - B
97.

if the function `f(x)=(x^2-(a+2)x+a)/(x-2)` for `x!=2` and `f(x)=2` for `x=2` is continuous function at `x=2` then value of` a` is:A. 2B. -1C. 1D. 0

Answer» Correct Answer - D
98.

If `f(x)` is continuous at `x=pi/2`, where `f(x)=(3^(x- pi/2)-6^(x- pi/2))/(cos x)` , for `x != pi/2`, then `f(pi/2)=`A. log 3B. log 6C. log 2D. log 18

Answer» Correct Answer - C
99.

If `f(x)` is continuous at `x = pi`, where `f(x)=(sqrt(2+cos x)-1)/((pi-x)^(2))", for " x!= pi`, then `f(pi)=`A. `1/4`B. `(-1)/(4)`C. `1/2`D. `(-1)/(2)`

Answer» Correct Answer - A
100.

If `f(x)` is continuous for all x, where `f(x)={:{((x^(2)-7x+12)/((x-2)^(2))", for "x!=2),(k ", for" x = 2 ):}`, then `k=`A. 7B. -7C. `pm7`D. None of these

Answer» Correct Answer - A