Question

Let g(x) be the reflection across the y-axis of the function f(x) = 5x + 8. Identify the rule for g(x).

A: g(x) = 5x − 8
B: g(x) = −5x + 8
C:g(x) = −5x − 8
D: g(x) = 5x + 8

Answer 1

Your answer would be: B

Explanation:

Answer 2

Option B: g(x) = −5x + 8

Explanation:

If we have a function f(x) and wish to make a function g (x) that is equal to the reflection of the function f(x) on the y-axis, then we must make the following transformation to f(x):

`g(x) = f(-x)`

In this case:

`f(x) = 5x +8`.

So when applying the transformation we obtain:

`g(x) = f(-x) = 5(-x) + 8`

Finally we have that

`g(x) = -5x +8`