[tex]\bf f(x)=-2x^2+11x\implies \left. \cfrac{df}{dx}=-4x+11 \right|_{x=9}\implies -4(9)+11\implies -25[/tex]
Answer:
a) -25
Step-by-step explanation:
First you have to find the derivative of F(x):
[tex]f(x)=2x^{2} +11x\\Derivative=2(2x)+1(11)\\Derivative=4x+11[/tex]
Now you just have to calculate the vale of f(x) when x=9
[tex]-4x+11=\\-4(9)+11=\\-36+11=-25[/tex]
So when x=9, the derivative of [tex]f(x)=2x^{2} +11x[/tex] is equal to -25
