Question

find g(x), where g(x) is the reflection across the y-axis of f(x) = 9x + 4.
options:
g(x) = 9x + 4
g(x) = 9x - 4
g(x) = -9x - 4
g(x) = -9x + 4

Explanation:

Step1: Recall reflection over y - axis rule

The rule for reflecting a function \(y = f(x)\) across the \(y\) - axis is \(g(x)=f(-x)\).

Step2: Substitute \(-x\) into \(f(x)\)

Given \(f(x)=9x + 4\), then \(f(-x)=9(-x)+4=-9x + 4\). So \(g(x)=-9x + 4\).

Answer:

\(g(x)=-9x + 4\) (the option corresponding to this formula)