H(x) = 1/9000x^2 - 7/15x + 500 = 1/9000(x^2 - 4200x + 4500000) = 1/9000(x^2 - 4200x + 4410000 + 90000) = 1/9000(x - 2100)^2 + 1/9000(90000) = 1/9000(x - 2100)^2 + 10
h(x) = 1/9000(x - 2100)^2 + 10
The solution to the system is (-2,-8)
X + 2y = 11
2x + y = 31
x = 11 - 2y
2(11 - 2y) + y = 31
22 - 4y + y = 31
3y = - 9
y = - 3
x = 11 - 2(-3)
x = 11 + 6
x = 17