I am not sure if I am on the right track with this problem and where do i go from here. Please help.

Problem: y=4x^2(7x^2+8)^(-2/3) find dy/dx. This is my solution so far:

-8x^2(14x/3(7x^2+8)^(5/3) + 8x/(7x^2+8)^(2/3)

-112x^3/3(7x^2+8)^(5/3) + 8x/(7x^2+8)^(2/3)

Where do I go from here?

Thank you in advance. Any help is greatly appreciated.