JAMB - Mathematics (2004 - No. 13)
Find the derivatives of the function y = 2x\(^2\)(2x - 1) at the point x = -1?
18
16
-4
-6
Giải thích
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