1)

$f(x)= \begin{cases} x \sin1/x& x \neq 0\\0& x = 0\end{cases} at x = 0 is$


A) continuous as well as differentiable

B) differentiable but not continuous

C) continuous but not differentiable

D) neither continuous nor differentiable

Answer:

Option C

Explanation:

For function to be continuous :

f(0+h) = f(0-h) = f(0)

f(0 + h) = $\lim_{h \rightarrow 0}h\sin1/h$ = 0 x (a finite quantity) = 0

f (0-h) = $\lim_{h \rightarrow 0}-h\sin1/-h$ = 0 x (a finite quantity) = 0
 

$\lim_{x \rightarrow 0}x\sin1/x$ = 0 x (a finite quantity) = 0

function is continuous at x = 0

For function to be differentiable :

f' (0 + h) = f'(0 - h)

$\frac{f(0+h)-f(0)}{h}$ = $\lim_{h \rightarrow 0}\frac{h \sin1/h - 0}{h}$

= $\lim_{h \rightarrow 0}\sin\left(\frac{ 1}{h}\right)$

which does not exist