It's the undertaker. Hi

a and c are the roots of the equation

Then

Equating coefficients

b and d are the roots of the equation

Then

Equating coefficients

We have a system of 4 equations

From (4):

Into (3): and into (1):

(2) into (1):

Hence c

Into (4):

N.B. When choosing values to input into the equation, if you let one of a,c,d be positive, then all the others have to be positive and vice-versa.

Possible values