1. The problem statement, all variables and given/known data Find all possible values of h. fh(a+bx+cx2+dx3) = [ a+b+c+hd b+c ] [ -b-c-hd hb ] 2. Relevant equations 3. The attempt at a solution 1) Row reduce the matrix [ a+b+c+hd b+c ] [ -b-c-hd hb ] to (R1+R2) [ a hb+ b+c ] [ 0 hb ] to (R1-R2) [ a b+c ] [ 0 hb ] a+b+c = 0 hb = 0 From this row reduction I assume b=0, a=1 and c=-1 h could still be any number though. So I got back to the original matrix. a+b+c+hd+b+c=0 -b-c-hd+hb=0 If I plug in the values I assumed (above) then I get d=-1 and h=-1 Is there a better / quicker way to do this? I seem to come across a lot of similar problems.