x^2 = 9x - y
y = x^2 - 9x
y = 3x + 5
x^2 - 9x = 3x + 5
x^2 - 12x - 5 = 0
Quadratic formula
x = (12 +- sqrt(144 + 20))/2
x = (12 +- sqrt(164))/2
x = (12 +- 2sqrt(41))/2
x = 6 +- sqrt(41)
y = 3x + 5
y = 6 +- 3sqrt(41) + 5
y = 11 +-3sqrt(41)
Solutions: x = 6 + sqrt(41), y = 11 + sqrt(41)
Solutions: x = 6 - sqrt(41), y = 11 - sqrt(41)