# The number of points,

Question:

The number of points, at which the function $f(x)=|2 x+1|-3|x+2|+\left|x^{2}+x-2\right|, x \in R$ is not differentiable, is

Solution:

$f(x)=|2 x+1|-3|x+2|+\left|x^{2}+x-2\right|$

$f(x)= \begin{cases}x^{2}-7 ; & x>1 \\ -x^{2}-2 x-3 ; & -\frac{1}{2}$\therefore f^{\prime}(x)=\left\{\begin{array}{lc}2 x ; & x>1 \\ -2 x-3 ; & -\frac{1}{2}

Check at $1,-2$ and $\frac{-1}{2}$

Non. Differentiable at $x=1$ and $\frac{-1}{2}$