Question

Find the derivative of f(x) = -2x2 + 11x at x = 9.a) -25b) -243c) 63d) 19

Answer 1

$\bf f(x)=-2x^2+11x\implies \left. \cfrac{df}{dx}=-4x+11 \right|_{x=9}\implies -4(9)+11\implies -25$

Answer 2

Answer:

a) -25

Step-by-step explanation:

First you have to find the derivative of F(x):

$f(x)=2x^{2} +11x\\Derivative=2(2x)+1(11)\\Derivative=4x+11$

Now you just have to calculate the vale of f(x) when x=9

$-4x+11=\\-4(9)+11=\\-36+11=-25$

So when x=9, the derivative of $f(x)=2x^{2} +11x$ is equal to -25