Don't know if I'm simplifying wrong or if it is a simple mistake but I cannot get the answer of 4. Please help and include exact step by step details. Thank you.
$$f(x)=x^3 + 2x^2 + 1,\;\;\;c= -2$$
[Math] Need help using the alternative formula to find the derivative at $x = c$
calculusderivatives
Best Answer
Judging from one of your comments, you’re probably supposed to calculate
$$\begin{align*} \lim_{x\to-2}\frac{f(x)-f(-2)}{x-(-2)}&=\lim_{x\to-2}\frac{x^3+2x^2+1-\left((-2)^3+2(-2)^2+1\right)}{x+2}\\\\ &=\lim_{x\to-2}\frac{x^3+2x^2}{x+2}\\\\ &=\lim_{x\to-2}\frac{x^2(x+2)}{x+2}\;; \end{align*}$$
can you finish it from there?