Given the following question:
[tex]y^2=x^2-9x+2[/tex]
Y^2 = x^2 - 9x +2
[tex]\begin{gathered} \sqrt[]{y^2}=^{}\pm x^2-9x+2 \\ \text{Plus or minus already lets you know that they're more than one value for y for ever value of x} \end{gathered}[/tex]
Your answer is no, the equation does not define y as a function of x.
