Question

Consider the function f(x) = (x + 1)2 - 1. Which of the following functions stretches

f(x) vertically by a factor of 4?
OA) f(x) = 1/4(x + 1)² - 4
B) f(x) = (¹/4x + 1)² + 3
OC) f(x) = 4(4x + 1)² - 1
OD)
f(x) = 4(x + 1)² - 1

Answer 1

Answer: Choice D

Reason:

The 4 out front quadruples the output of (x+1)^2, which makes the graph 4 times as tall compared to before. This is why we go for choice D.

Choice C is close, but that 4x inside the parenthesis should be x. The 4x horizontally compresses the graph by a factor of 4, and it horizontally moves the graph when we simply want to vertically dilate it. This is why choice C is ruled out.