# Thread: derrivative of an absolute value

1. ## derrivative of an absolute value

y=ln l 2-x-5x^2 l how would i approach this?

2. You can never take the log of a negative number.

Suppose ln(-2) exists, then there exists some a such that e^a = -2, never true in the reals.

Just use the chain rule, the absolute values shouldn't matter, correct me if I'm wrong.