MCQ
The function $f(x) = {x^2}\,\,\sin \frac{1}{x},\,x \ne \,0,\,\,f(0)\, = 0$ at $x = 0$
  • A
    Is continuous but not differentiable
  • B
    Is discontinuous
  • C
    Is having continuous derivative
  • Is continuous and differentiable

Answer

Correct option: D.
Is continuous and differentiable
(d)
$\mathop {\lim }\limits_{x \to 0} f(x) = {x^2}\sin \left( {\frac{1}{x}} \right)$, but $ - 1 \le \sin \left( {\frac{1}{x}} \right) \le 1$ and $x \to 0$
$\therefore $ $\mathop {\lim }\limits_{x \to {0^ + }} f(x) = 0 = \mathop {\lim }\limits_{x \to {0^ - }} f(x) = f(0)$
Therefore $f(x)$ is continuous at $x = 0$. 
Also, the function $f(x) = {x^2}\sin \frac{1}{x}$ is differentiable because 
$Rf'(x) = \mathop {\lim }\limits_{h \to 0} \frac{{{h^2}\sin \frac{1}{h} - 0}}{h} = 0$, 
$Lf'(x) = \mathop {\lim }\limits_{h \to 0} \frac{{{h^2}\sin (1/ - h)}}{{ - h}} = 0$.

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

If $n $ is a positive integer, then ${\left( {\sqrt 3 + 1} \right)^{2n}} - {\left( {\sqrt 3 - 1} \right)^{2n}}$ is
Let $f: R \rightarrow R$ satisfy the equation $f(x+y)=f(x) \cdot f(y)$ for all $x, y \in R$ and
$f ( x ) \neq 0$ for any $x \in R .$ If Ihe function $f$ is differentiable at $x =0$ and $f^{\prime}(0)=3,$ then $\lim _{h \rightarrow 0} \frac{1}{h}(f(h)-1)$ is equal to ....... .
$\lim _{x \rightarrow \frac{\pi}{2}}\left(\frac{1}{\left(x-\frac{\pi}{2}\right)^2} \int_{x^2}^{\left(\frac{\pi}{2}\right)^3} \cos \left(\frac{1}{t^3}\right) dt \right)$ is equal to
The area bounded between the parabola $y^2 = 4x$ and the line $2x + y -4 = 0$ is
The mean of the numbers obtained on throwing a die having written $1$ on three faces, $2$ on two faces and $5$ on one face is
If $f(x) = {x^{11}} + {\sin ^3}\left( {35x} \right) + 111x$ , then the value of ${f^{ - 1}}\left( {\sin \frac{\pi }{5}} \right) + {f^{ - 1}}\left( {\sin \frac{{6\pi }}{5}} \right) + {f^{ - 1}}\left( {\sin \frac{\pi }{7}} \right) + {f^{ - 1}}\left( {\sin \frac{{8\pi }}{7}} \right)$ is equal to
If a unit vector $\vec r$ makes angles $\frac{\pi }{3}$ with $\hat i$, $\frac{\pi }{4}$ with $\hat j$ and $\theta  \in \left( {0,\pi } \right)$ with  $\hat k$, then a value of $\theta$ is
Let the shortest distance between the lines $\frac{x-3}{3}=\frac{y-\alpha}{-1}=\frac{z-3}{1}$ and $\frac{x+3}{-3}=\frac{y+7}{2}=\frac{z-\beta}{4}$ be $3 \sqrt{30}$. Then the positive value of $5 \alpha+\beta$ is
If for the complex numbers $z$ satisfying $|z-2-2 i| \leq 1$, the maximum value of $|3 i z+6|$ is attained at $\mathrm{a}+i \mathrm{~b}$, then $\mathrm{a}+\mathrm{b}$ is equal to .... .
In a touring cricket team there are $16$ players in all including $5$ bowlers and $2$ wicket-keepers. How many teams of $11$ players from these, can be chosen, so as to include three bowlers and one wicket-keeper