9x² - 25y² = 225 for T subscript(0, -5)

This is what I did:

9x² - 25(y + 5)² = 225

9x² - 25y² - 250y - 850 = 0

So to graph it I have to rewrite the general form equation in quadratic form, ay² + by + c = 0, and then solve for y with the quadratic formula:

(-25)y² + (-250)y + (9x² - 850) = 0

y = {250±√[(-250)² - 4(-25)(9x² - 850)]} / 2(-25)

But when I try to graph it on a calculator it doesn't work. Help please!