**Absolute value - Wikipedia**
https://en.wikipedia.org/wiki/Absolute_value

The real absolute value function is continuous everywhere. It is differentiable everywhere except for x = 0. It is monotonically decreasing on the interval (−∞, 0] and monotonically increasing on the interval [0, +∞). Since a real number and its opposite have the same absolute value, it is an even function, and is hence not invertible. The real absolute value function is a piecewise linear, convex function.

**DA:** 17 **PA:** 25 **MOZ Rank:** 25