Since it is true for ALL x, let's choose x=0:



for x=0














So replace c by 6-a

in





Again, since it is true for ALL x, let's choose x=1:















So substitute a+1 for b in





Again, since it is true for ALL x, let's choose x=-1:















Substitute in





Substitute in





So a=3, b=4, c=3.

Edwin