Question

Which function has an inverse that is also a function?

g(x) = 2x - 3
k(x) = -9x2
f(x) = 5x + 21
(x) = -20

Answer 1

Answer: 1st, 3rd, and 4th functions

Explanation:

Assuming k(x)=9x^2, all the other functions have inverses because they are linear, meaning they must be one-to-one.