I need to find the value of k=3

PROBLEM: Evaluate and simplify f(x) =x3 + k for {f(x+Ax)-f(x)}/Ax. Include the ENTIRE equation for f(x) as your first line of your post. Use "^" for exponent in your title. The value of k is different for EACH DIFFERENT STUDENT. Student 1 --> k=1, Student 2 --> k=2, etc