2x + y = 1, x^2 + y^2 = 1

1 : 2x + y = 1 y = 1 - 2x2 : x^2 + (1-2x)^2 = 1 x^2 + (1-2x)(1-2x) = 1 x^2 + 1 - 2x - 2x + 4x^2 = 1 5x^2 - 4x + 1 = 1 5x^2 - 4x = 0 x(5x - 4) = 0 x = 0, x = 4/5 y = 1, y = -3/5