$($a$)$ Determine $f(xh).$ Simplify your answer as much as possibie.

$f(xh)=3(xh{)}^{2}2$

$f(xh)=3(x^2{h}^{2}2hx)2$

$f(xh)=3x^{2}3h^{2}6hx2$

$($b$)$ Using your answer from $($a$),$ determine $\frac{f(xh)-f(x)}{h}.$ Simplify your answer as much as possible.

$($c$)$ Using your answer from $($b$),$ compute the following limit$.$

$\underset{h0}{lim}\frac{f(xh)-f(x)}{h}$