Choose the one alternative that best completes the statement or answers the question.
Find the slope of the tangent line to the graph at the given point.
-$$f ( x ) = x ^ { 2 } + 5 x \text { at } ( 4,20 )$$
A) 3
B) 21
C) 13
D) 9

Question

Quizplus · Accepted Answer

The slope of the tangent line to the graph of $f(x) = x^2 + 5x$ at any point can be found by taking the derivative of $f(x)$ with respect to $x$, which gives $f'(x) = 2x + 5$. Substituting $x = 4$ into $f'(x)$ gives $f'(4) = 2(4) + 5 = 8 + 5 = 13$.

Choose the One Alternative That Best Completes the Statement or Answers