Answer:
the value of x when f(x) = 15 is 3.5.
Explanation:
We are given that:
f(x) = 1 + 4x
We need to find the value of x when f(x) = 15.
So we can set up the equation:
1 + 4x = 15
Subtracting 1 from both sides, we get:
4x = 14
Dividing both sides by 4, we get:
x = 14/4
Simplifying, we get:
x = 3.5
Therefore, the value of x when f(x) = 15 is 3.5.