We can write a quadratic equation with roots a and b as:
(x - a)(x - b) = 0
=> x^2 - (a+b)x + ab = 0
as the product of the roots is -3.
=> x^2 - ( a + b) - 3 = 0
Now a and b can have several values which satisfy the condition that their product is -3, e.g. (-1 , 3) , ( 3/2 , -2) etc. We are not given any further information about what the roots are.
Therefore the quadratic equation is
x^2 - (a + b) - 3 = 0