若(3x^2-2x+1)(x+b)的积

问题描述:

若(3x^2-2x+1)(x+b)的积

(3x^2-2x+1)(x+b)
=x*(3x^2-2x+1)+b*(3x^2-2x+1)
=3x^3-2x^2+x+3bx^2-2bx+b
=3x^3+x^2(3b-2)+x(1-2b)+b