MCQ
$f:[-1,1] \rightarrow R$ be a function defined by $f(x)=\left\{\begin{array}{cl}x^2 \mid \cos \left(\frac{\pi}{x}\right) & \text { for } x \neq 0 \\ 0 & \text { for } x=0\end{array}\right.$

The set of points where $f$ is not differentiable is

  • A
    $\{x \in[-1,1]: x \neq 0\}$
  • B
    $\left\{x \in[-1,1]: x=0\right.$ or $\left.x=\frac{2}{2 n+1}, n \in Z\right\}$
  • $\left\{x \in[-1,1]: x=\frac{2}{2 n+1}, n \in Z\right\}$
  • D
    $[-1,1]$

Answer

Correct option: C.
$\left\{x \in[-1,1]: x=\frac{2}{2 n+1}, n \in Z\right\}$
c
(c)

We have,

$f(x)=\left\{\begin{array}{cc} x^2 \mid \cos \left(\frac{\pi}{x}\right) & \text { for } x \neq 0 \\ 0 & \text { for } x=0 \end{array}\right.$

$f(x)$ is not differentiable at

$\cos \frac{\pi}{x} \mid =0$

$\cos \frac{\pi}{x} =0 \Rightarrow \frac{\pi}{x}=(2 n+1) \frac{\pi}{2}$

$\cos \frac{\pi}{x}=0 \Rightarrow \frac{\pi}{x}=(2 n+1) \frac{\pi}{2}$

$x=\frac{2}{2 n+1}$

$\because f(x)$ is not differentiable at

$x \in[-1,1]: x=\frac{2}{2 n+1}, n \in Z$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

There are $3$ bags, each containing $5$ white balls and $3$ black balls. Also there are $2$ bags, each containing $2$ white balls and $4$ black balls. A white ball is draws at rondom. Find the probability that this white ball is from a bag of the first group.
$\int_{}^{} {\frac{{dx}}{{1 + x + {x^2} + {x^3}}} = } $
Evaluate: $\int \frac{x-4}{(x-2)^3} \cdot e^x d x$
If $a\,.\,b = b\,.\,c = c\,.\,a = 0$ , then what is the value of the scalar triple product $ [a b c] $ ?
Water is drained from a vertical cylindrical tank by opening a valve at the base of the tank. It is known that the rate at which the water level drops is proportional to the square root of water depth $y$, where the constant of proportionality $k$ $>$ $0$ depends on the acceleration due to gravity and the geometry of the hole. If t is measured in minutes and $k$ = $\frac{1}{15}$ then the time to drain the tank if the water is $4$ meter deep to start with is .......... $\min.$
If $A = \left( {\begin{array}{*{20}{c}}3&2\\0&1\end{array}} \right)$, then ${({A^{ - 1}})^3}$is =
If $\text{y}=\tan^{-1}\Big\{\frac{\log(\frac{\text{e}}{\text{x}})^2}{\log(\frac{\text{e}}{\text{x}})^2}\Big\}+\tan^{-1}\Big(\frac{3-2\log,\text{x}}{1-6\log,\text{x}}\Big)$ then $\frac{\text{d}^2\text{y}}{\text{dx}^2}=$
  1. 2
  2. 1
  3. 0
  4. -1
Solving an integer programming problem by rounding off answers obtained by solving it as a linear programming problem (using simplex), we find that.
  1. The values of decision variables obtained by rounding off are always very close to the optimal values.
  2. The value of the objective function for a maximization problem will likely be less than that for the simplex solution.
  3. The value of the objective function for a minimization problem will likely be less than that for the simplex solution.
  4. All constraints are satisfied exactly.
  5. None of the above.
If $\text{f}(\text{x})=\frac{\sin^{-1}\text{x}}{\sqrt{1-\text{x}}^2},$ then $(1-\text{x})^2\text{f}''(\text{x})-\text{xf}(\text{x})=$
  1. 1
  2. -1
  3. 0
  4. None of these
A ball thrown vertically upwards falls back on the ground after  $6$ second. Assuming that the equation of motion is of the form $s = ut - 4.9{t^2}$, where s is in metre and  $t$ is in second, find the velocity at $t = 0$ .......... $m/s$.