# Math Help - How to get the critical numbers?

1. ## How to get the critical numbers?

Question:
$x(4-x^2)^\frac{1}{2}$

Attempt:
$y'= (x) * \frac{1}{2}(4-x^2)^\frac{-1}{2}*(-2x)+(4-x^2)^\frac{1}{2}*(1)$

After this step i dont know how to simplify?

Please anwer in steps
Thank you.

2. You can multiply the right side by [2(4-x^2)^(1/2)]/[2(4-x^2)^(1/2)]
you should end up with [4-2x^2]/[(4-x^2)^(1/2)]