===================================================
Explanation:
Rearrange 0 = x + 2 + x^2 into x^2 + x + 2 = 0
Note that we have something in the form ax^2 + bx + c = 0
where a = 1, b = 1, c = 2
Plug these three values into the discriminant formula
d = b^2 - 4ac
d = 1^2 - 4*1*2
d = 1 - 8
d = -7
