Answer :
[tex]x=0\\
\\
9x^2+9y=81\\
\\
9.0^2+9y=81\\
\\
9y=81\\
\\
y=\frac{81}{9}\\
\\
\boxed{y=9}[/tex]
[tex]y=0\\ \\ 9x^2+9.0=81\\ \\ 9x^2=81\\ \\ x^2=\frac{81}{9}\\ \\ x^2=9\\ \\ \boxed{x= \pm 3}[/tex]
[tex]y=0\\ \\ 9x^2+9.0=81\\ \\ 9x^2=81\\ \\ x^2=\frac{81}{9}\\ \\ x^2=9\\ \\ \boxed{x= \pm 3}[/tex]
