If f (x) = x + 5, for what value of x does f (4x) = f (x + 4) ?

x = 4/3

Step-by-step explanation:

To solve find f (4x) and f (x+4). You should get f (4x) = 4x + 5 and f (x+4) = x + 9. Now, set the two equations equal to each other.

f (4x) = f (x + 4)

4x + 5 = x + 9

3x = 4

x = 4/3