Question

Find the derivative of f(x) = -12x2 + 9x at x = 6.

Answer 1

\[\frac{ d }{ dx }(-12x ^{2}+9x)=(2)(-12)x ^{2-1}+(1)9x ^{1-1}\]
\[=-24x+9|_{6}=(-24)(6)+9=-144+9=-135\]

Answer 2

derivatives follow the form
\[nx ^{n-1}=\frac{ dy }{ dx }\]