1) 2x - y = 1 or y = 2x - 1
2) x^2 - xy = -6
substitute eq(1) into eq(2):
x^2 - x(2x - 1) = -6
x^2 - 2x^2 + x = -6
-x^2 + x + 6 = 0
using quadratic formula:
x = (-1 +/- SQR(1 - 4(-1)(6)))/2(-1)
x = (-1 +/- 5)/-2
x = -2, 3
using eq(1):
y = 2x -1
y = 2(-2) - 1 = -5
y = 2(3) - 1 = 5
solutions are (-2,-5) and (3,5)