#### Answer

(a) $f(x)=3x^2+x+2$
(b) $(3)=32$

#### Work Step by Step

(a) function notation.
Solve for $y$:
\begin{array}{ccc}
&y-3x^2&=&2+x
\\&y-3x^2+3x^2&= &2+x+3x^2
\\&y&=&3x^2+x+2
\end{array}
Let $y=f(x)$. The equation becomes:
$$f(x)=3x^2+x+2$$
(b) To find $f(3)$, substitute $3$ to $x$ in $f(x)$ to obtain:
$f(x)= 3x^2+x+2
\\f(3) = 3(3^2)+3+2
\\f(3)=3(9)+3+2
\\f(3)=27+3+2
\\f(3)=32$