Question

Given f(x)=x^2+4x+5, what is f(2+h)-f(2)/h equal to?A. h^2 + 8hB. 2x + h + 4C. 8 + hD. h + 4

Answer 1

ANSWER:

C. 8 + h

STEP-BY-STEP EXPLANATION:

We have the following expression:

$f\mleft(x\mright)=x^2+4x+5$

We evaluate each case and obtain the following:

$\begin{gathered} f(h+2)=\left(2+h\right)^2+4\left(2+h\right)+5 \\ \\ f(2+h)=4+4h+h^2+8+4h+5 \\ \\ f(2+h)=h^2+4h+4h+4+8+5 \\ \\ f(2+h)=h^2+8h+17 \\ \\ \\ f(2)=\left(2\right)^2+4\left(2\right)+5 \\ \\ f(2)=4+8+5 \\ \\ f(2)=17 \end{gathered}$

We substitute each function evaluated to determine the final result, just like this:

$\begin{gathered} \frac{f(2+h)-f(2)}{h}=\frac{h^2+8h+17-17}{h} \\ \\ \frac{f(2+h)-f(2)}{h}=\frac{h^2+8h}{h} \\ \\ \frac{f(2+h)-f(2)}{h}=h+8=8+h \end{gathered}$

Therefore, the correct answer is C. 8 + h