Does a vertical line represent a function? (Full video)

Khan Academy

Supporting grades: 8

Description: Explaining why a vertical line doesn't represent a function. Created by Sal Khan. It should spit out exactly one value of y. If it spits out multiple values of y, we don't know what f of x is going to be equal to. So let's see if, for this graph, whether for a given x it spits out exactly one y.

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