Question

{x^2+2y^2=18
{ y-x=3

Answer 1

$x^{2} + 2y^{2} = 18 \\ y - x = 3 \\ \\ \\ x ^{2} + 2y^{2} = 18 \\ x = - 3 + y \\ \\ \\ ( - 3 + y)^{2} + 2y ^{2} = 18 \\ \\ y = 3 \\ y = - 1 \\ \\ \\ x = - 3 + 3 \\ x = - 3 - 1 \\ x = 0 \\ x = - 4$