You can put this solution on YOUR website!
Ellipses do not have asymptotes. Hyperbolas do. Did you mean
"hyperbola" and typed "ellipse" instead? I will assume that's
what you did.
Since one asymptote is y = x, the othe one is y = x.
We draw those, plot the vertices (9,0) and (-9,0), and and sketch the hyperbola to approach them.
Then we draw in the defining rectangle:
By letting x=4 and -4 in each of those asymptote equations we can
see that the corners of the defining rectangle are:
(9,), (9,), (-9,), and (-9,)
so a = 9 and b = , so the equation is
- = 1