I worked it down to
and then
x = 5
a= 1
x = -1
-12 = b
whats confusing me is that if i let x = -1 for c i would get -12 = C0 which is -12 = 0
is my equation wrong?
Never thought about doing the question like that but lets roll with it...
If x=5, everything bu the A term is 0 so we get...
216A = 216.
So A = 1.
If x=-1, everything but the D term cancels and you get...
-6D = -12, D = 2
Now set x to be something generic like 0.
Chances are you'll get something like ...B + ...C = -9
Then set x to be something else. Like 1 for example.
Once again you'll get an equation involving B and C.
Solve for B and C using simultaneous equations.