x=(1,-3)
x^2 + 2x -1 = 2. {x^2 + 2x} -1 = 2. The equation in the bracket MUST equal 3 because -1 it equals 2. x could equal 1 because 1^2+2*1-1=2, right. Then again, x could equal -3 because -3^2(=9)+2*(-3)(=-6)-1=2. So the final equation equals 9+(-6)-1=2
