If $f(x) = -3x^3 + 2x^2$, find $f(-1)$ and $f(1/2)$. I hope you can help me out
For number 8 and 9 find each value if $f(x) = -3x^3 + 2x^2$
8) $f(-1)$ 
9) $f(1/2)$

If you've given some $f(x)$ and asked to find out $f(a)$ 
then you have to replace all $x$ by $a$ and then simplify ( If you cannot calculate ) resultant expression.
for example
if $$f(x)=-3x^3+2x^2$$
then $$f(-1)=-3(-1)^3+2(-1)^2=5$$
and $$f\left(\frac{1}{2}\right)=-3\left(\frac{1}{2}\right)^3+2\left(\frac{1}{2}\right)^2=\frac{1}{8}$$
