Question

The limit represents f '(c) for a function f(x) and a number c. Find f(x) and c.

lim [7 (sqrt x) -21] / (x-9)
x-> 9

Answer 1

\[\large \lim_{{x \to 9}} \frac{7 \sqrt x -21}{x-9}\]

hit it with l''Hospital's rule

Answer 2

\[\frac{7(\sqrt x - 3)}{(\sqrt x^2 -3^2)}\]

Answer 3

nicer