Answer:
x = 1/4, -1
Step-by-step explanation:
To solve for f(3x), we plug in f(3x) into our quadratic to get 12x^2 + 9x - 3
When we factor, we can take 3 out so we have 4x^2 + 9x - 3
After factoring, we will be left with 3(4x-1)(x+1)
4x - 1 = 0
So x = 1/4
x + 1 = 0
So x = -1
Best of luck
