y = 2x\(^2\)(2x - 1)

expand the bracket

y = 4x\(^3\) - 2x\(^2\)

\(\frac{\text{dy}}{\text{dx}}\) = 12x\(^2\) - 4x
at x = -1
\(\frac{\text{dy}}{\text{dx}}\) = 12(-1)\(^2\) - 4(-1)
= 12 + 4
= 16