Question

Choose between ones that are slashed

Answer 1

$\textbf{You have to}$ restrict the domains of quadratic functions and absolute value functions, because these functions are $\textbf{many-to-one}$ functions. For instance, the quadratic function f(x) = x^2 pairs both −2 and 2 with 4, and the absolute value function f(x) = |x| pairs both −2 and 2 with 2.

Linear functions (excluding constant functions) and exponential functions are $\textbf{one-to-one}$ functions, so their domains $\textbf{do not need}$ to be restricted.
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An absolute value function, without domain restriction, has an inverse that is NOT a function.

In order to guarantee that the inverse must also be a function, we need to restrict the domain of the absolute value function to make it a one-to-one function.