Is y=x^2 a function

Answer 1

Hi Jack,

Yes it is. Using the definition of a function, y=x^2 is a function because for every x-value in your domain, you will only get 1 unique y-value.

A quick check you can do is to use the vertical line test. The function y=x^2 is a parabola and if you draw vertical lines anywhere in your parabola, the vertical lines will only cross the parabola once. Which makes it a function. An example that is not a function is a circle because when you draw a vertical line on a circle, it crosses at 2 different points.

Answer 2

Yes, because every x-value returns a unique y-value. On the other hand, x = y² is not a function because every x-value does not point to a single y-value.