### Home > APCALC > Chapter 4 > Lesson 4.2.1 > Problem4-47

4-47.

Use the Power Rule to write an equation for $f^\prime$ given $f\left(x\right) = \left(x^{2} + 1\right)\left(x – 4\right)$ by first expanding $f$. Then, write the equation of the line tangent to $f$ at $x = –3$.

Write the tangent line in point-slope form.

Which function, $f\left(x\right)$ or $f '\left(x\right)$, can be used to find the slope? Which can be used to find the point?