Question

I cant figure out any of these problems! I would love some help!

Answer 1

Check the picture below.

$\bf \begin{cases} h=0\\ k=0\\ a=25\\ b=20 \end{cases}\implies \cfrac{(x-0)^2}{20^2}+\cfrac{(y-0)^2}{25^2}=1\implies \cfrac{x^2}{400}+\cfrac{y^2}{625}=1$