### Home > PC3 > Chapter 13 > Lesson 13.3.2 > Problem13-114

13-114.

Use the definition of instantaneous rate of change to show that the equation of the tangent line to the curve $y=12\sqrt{x}$ at the point $\left(4, 24\right)$ is $y = 3x + 12$.

You are given a point, so now you need the slope of the tangent line.
Use the point - slope form for a linear function.

$m= \lim \limits_{ h \to 0}\frac{12\sqrt{4+h}-12\sqrt{4}}{h}$