Using the function concept, it is found that [tex]x^2 + y^2 = 100[/tex] is not a function, as for each value of x there is more than one corresponding value of y.
In this problem, the relation is:
[tex]x^2 + y^2 = 100[/tex]
For example, considering x = 0, the corresponding values of y are:
[tex]0^2 + y^2 = 100[/tex]
[tex]y = \pm \sqrt{100}[/tex]
[tex]y = \pm 10[/tex]
Hence, it is not a function, as for each value of x there is more than one corresponding value of y.
To learn more about the function concept, you can take a look at