Question

Which functions are invertible? Select each correct answer.

Answer 1

They are `A` and `D`. See explanation.

Explanation:

A function is invertible if and only if it takes each value only once. This is true for `A` and `D`.

For other functions this statement is false.

For example function in `C` takes `0` for `x_1=-4` and `x_2=4`.

Function `B` also has 2 zeros. They are `0` and `3`.