Let $\displaystyle f(x) = 2x^{4}-5x^{2}-5$.

(a) Find $f'(x)$.

$f'(x)$ =

(b) Find the slope of the line tangent to the graph of $f$ at $x = 3$.

Slope at $x = 3$:

(c) Find an equation of the line tangent to the graph of $f$ at $x = 3$.

Tangent line: $y$ =