Thanks. Parameter Method.
If there are n factors,we have to use n-2 Parameters.
(a1+b1x)(a2+b2x)......(an+bnx)={[(c3c4...cna1-(c3b3+...cnbn)x](a2+b2x)(c3a3+c3b3x)...(cnan+cnbnx)}/c3c4...cn....We get n equations,but only n-1 is independent.We can get x.