Answer:
Step-by-step explanation:
f(x) is simply another way of saying y
We are told that y = 15, so we set the equation 18x² + 15x - 10 equal to 15.
Add 10
18x² + 15x = 25
18x² + 15x + 25 = 0
Factor
(6x − 5) (3x + 5) = 0
Find both solutions for x
6x - 5 = 0
6x = 5
x = 5/6
Now, for the other solution.
3x + 5 = 0
3x = -5
x = -5/3