What is the vertical and horizontal line tests for 1-1 function?
A graph of a 1-1 function needs to pass both the vertical line test and the horizontal line test.
A graph will represent a function, if any vertical line drawn crosses it only once. If the function is also 1-1, then any horizontal line drawn will cross it only once. If the horizontal line crosses the graph more than once, the function is not 1-1.