In a quadratic equation , m is the sum of the roots, and n is the product of the roots.
So from the second equation, we have (1). And (2)
And from the first one, we have (3) and (4)
From (4), we get c=0
Substituting in (3), we get b=0
Substituting in (1), we get d=0
Then, a can take any values you want...