Find the equation of the tangent line to y = f(x) = 4x at x = 5.
A) y = 4x - 5
B) y = 4x
C) y = -4x
D) y = 4x + 5
E) y = 4x - 20

Question

Quizplus · Accepted Answer

The derivative of $f(x) = 4x$ is $f'(x) = 4$, which is the slope of the tangent line at any point on the curve. At $x = 5$, the slope remains $4$, and since the equation of the tangent line must have the same slope as the curve at that point, the equation is $y = 4x$, which matches option B.

Find the Equation of the Tangent Line to Y =