Is my solution correct? Differentiate $y = \left(x + \left(x + \sin^2 x\right)^4\right)^6$ 
Differentiate $y = \left(x + \left(x + \sin^2 x\right)^4\right)^6$.

I am unsure if I skipped a step in the end. Please take a look at my work. Criticize my strategy, point out obvious math deficiencies, or why I am missing the obvious. 

derivative of $\sin^2(x)$ is $2\sin(x)\cos(x)$, also don't omit parentheses
