## Calculus (3rd Edition)

$f$ is increasing on (-1,$\infty$)
Define $f(x) = | x+1 |$ as two separate cases, When $x\leq -1$, $f(x) = -(x+1)$ $\implies$ $f'(x) = -1$, which means $f$ is decreasing When $x>-1$, $f(x) = x+1$ $\implies$ $f'(x) = 1$, which means $f$ is increasing