Part $1$: The derivative at a specific point

Use the definition of the derviative to compute the derivative of $f(x)=1-3x^2$ at the specific point $x=2.$ Evaluate the limit by using algebra to simplify the difference quotient $($in first answer box$)$ and then evaluating the limit $($in the second answer box$).$

$f^{\text{'}}(2)=\underset{h0}{lim}(\frac{f(2+h)-f(2)}{h})=\underset{h0}{lim}()=$

Part $2$: The derivative function

Part $3$: The tangent line

Note: You can earn partial credit on this problem.