Practicing Success
The function f : R → R given by f(x) = -lx - 1| is |
continuous as well as differentiable at x = 1 not continuous but differentiable at x = 1 continuous but not differentiable at x = 1 neither continuous nor differentiable at x = 1 |
continuous but not differentiable at x = 1 |
$f(x)=-|x-1|$ so $f(x)=\left\{\begin{array}{rr}-(x-1) & x \geq 1 \\ (x-1) & x<1\end{array}\right.$ since x is zero at x = 1 so $f(x)=\left\{\begin{array}{rr}-1 & x \geq 1 \\ 1 & x<1\end{array}\right.$ So $\lim\limits_{x \rightarrow 1^{-}} f(x)=-(1-1)=0$ = LHL (left hand limit) $\lim\limits_{x \rightarrow 1+} f(x)=(1-1) = 0$ = RHL (Right hand) $f(1)= -|1-1|=0$ ⇒ f(1) = LHL = RHL (continuous) so $\lim\limits_{x \rightarrow 1^{-}} f'(x) =-1$ = LHD (left hand derivative) $\lim\limits_{x \rightarrow 1^{+}} f(x)=1$ = RHD (right hand derivative) as LHD ≠ RHD so not differentiable at x = 1 |