<em>Step #1: </em> Make sure the equation is in the form of [ Ax² + Bx + C = 0 ].
Yours is already in that form. A = 1 B = 2 C = -2
<em>Step #2:</em> The 'discriminant' for that equation is [ B² - 4 A C ]. That's all there is to it, but it can tell you a lot about the roots of the equation.
-- If the discriminant is zero, then the left side of the equation is a perfect square, and both roots are equal.
-- If the discriminant is greater than zero, the the roots are real and not equal.
-- If the discriminant is less than zero, then the roots are complex numbers.
The discriminant of your equation is [ B² - 4 A C ] = 2² - 4(1)(-2) = 4 + 8 = 12