4x^n+3-12x^n+2+9^n+1等于多少?
问题描述：
4x^n+3-12x^n+2+9^n+1等于多少?
答
4x^(n+3)-12x^(n+2)+9^(n+1)
=x^(n+1)×(4x^2-12x+9)
=x^(n+1)×(2x-3)^2