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The gradient of the curve $y=-2x^{3}+3x+5$ at $x=2$ is

$\begin{array}{1 1}(1)-20&(2)27\\(3)-16&(4)-21\end{array}$

Can you answer this question?

$y= -2x^3+3x+5$
$\large\frac{dy}{dx}$$=-6x^2+3 \large\frac{dy}{dx}$$x=2 => -6 \times 2^2 +3 =-24 +3 =-21$
Hence 4 is the correct answer.
answered May 16, 2014 by