Note:
Your function is a little ambiguous. I think you may have tried to write your function such as:
f(x) = 4x + 3
I am assuming your function as:
f(x) = 4x + 3
Answer:
The value of f(3) = 15
Explanation:
Given
Assuming the function is
f(x) = 4x + 3
To determine
The value of f(3)
The value of f(3) can be determined by substituting x = 3 in the function
f(x) = 4x + 3
substitue x = 3 in the function
f(3) = 4(3) + 3
f(3) = 12 + 3
f(3) = 15
Therefore, the value of f(3) = 15