Answer
$f(0)=0$
$f(3)=15$
$f(-3)=3$
$f(a)=a^{2}+2a$
$f(-x)=x^{2}-2x$
$f( \frac{1}{a})=\frac{1}{a^{2}}+\frac{2}{a}$
Work Step by Step
We are given:
$f(x)=x^{2}+2x$
We evaluate:
$f(0)=0^{2}+2(0)=0+0=0$
$f(3)=3^{2}+2(3)=9+6=15$
$f(-3)=(-3)^{2}+2(-3)=9-6=3$
$f(a)=a^{2}+2(a)=a^{2}+2a$
$f(-x)=(-x)^{2}+2(-x)=x^{2}-2x$
$f( \frac{1}{a})=(\frac{1}{a})^{2}+2(\frac{1}{a})=\frac{1}{a^{2}}+\frac{2}{a}$
