No. If you solve it for [tex]y[/tex], you have
[tex]y=\pm\sqrt{x^2+100}[/tex]
So, given a certain value for [tex]x[/tex], say [tex]x=0[/tex], you have
[tex]y=\pm\sqrt{100}=\pm10[/tex]
So, you're associating two y-values for each x value. This implies that this is not a function.
