Question 954742
{{{x^2-8x+9y^2=-7}}}


{{{(x^2-8x+16)+9y^2-16=-7}}}


{{{(x-4)^2+9y^2=-7+16}}}


{{{(x-4)^2+9y^2=9}}}


{{{highlight((x-4)^2/9+y^2=1)}}}
Understanding Completing The Square is necessary.