Simultaneous Equation

Solve for x and y

x² + xy = 8   ---------------------  (1)

x - y = 6    ------------------------ (2)

We have y = x – 6 from (2)

Substituting in (1) we get

x² + x(x – 6) = 8   

or, x² – 3x – 4 = 0

or, x = 4, -1