Select ALL equations that represent an ellipse.

$x^2-8y^2=0$

$a=(y-2{)}^2$

$y=3x^2+2$

$x^2+3y^2=2$

$\frac{(x-5{)}^2}{8}-\frac{(y+5{)}^2}{4}=1$

$x^2-3y^2=2$

$\frac{(x-5{)}^2}{8}+\frac{(y+7{)}^2}{4}=1$