Since you know that the roots are a and b, the quadratic can be written as (x - a)(x - b) = 0
(x - a)(x - b) = 0 ---> x2 - ax - bx + ab = 0 ---> x2 + (-a -b)x + ab = 0
We are given that the equation is: x2 + ax + b = 0
Comparing these two equations, we see that a = -a - b and b = ab
If b = ab, a must be 1.
If a = -a - b ---> 2a = - b ---> b = -2a
Since a = 1 ---> b = -2
I believe that there is only one ordered pair, (1, -2)