You can put this solution on YOUR website! x^2/9 - y^2/81 = 1
This is a horizontal hyperbola with center (0,0).
a = 3
b = 9
Box Points: (3,9), (-3,9), (3,-9), and (-3,-9)
m = +-3
y = m(x - x1) + y1
y = 3(x - 3) + 9 and y = -3(x + 3) + 9
y = 3x and y = -3x