Precalculus: Functions

Problem : Decide whether the graph below is a function.

Problem : Decide whether the graph below is a function.

Problem : Decide whether the graph below is a function.

Problem : What is the domain and range of the function f (x) = ?

Problem : What is the domain and range of the function f (x) = ?

Problem : Is the following a function: y = ±x ?

Problem : Is the following a function: y = | x| ?