(mx²+nx+1)(2a²-3x+1)=2a²mx²-3ax³+mx²+2a²nx-3nx²+nx+2a²-3x+1
=(2a²m+m-3n)x²-3ax³+(n-3+2a²n)x+1
因为不含x²、x项,所以
n-3+2a²n=0 n=3/(1+2a²)
2a²m+m-3n=0 m=9/(1+2a)²
m+n=(9+3+6a²) /(1+2a²)=(12+6a²)/(1+2a²)
多项式(mx平方+nx+1)与(2x平方-3x+1)的积
=2mx^4-3mx^3+mx^2+2nx^3-3nx^2+nx+2x^2-3x+1
=2mx^4+(2n-3m)x^3+(m-3n)x^2+(n-3)x+1
不含x平方与x项,
则 m-3n=0
n-3=0
n=3 m=9
m+n=12