x^4+2x^3+6x^2+4x+8
=x^4+6x^2+8+2x^3+4x
=(x^2+2)(x^2+4)+2x(x^2+2)
=(x^2+2)(x^2+4+2x)=x^4+6x^2+8+2x^3+4x=(x^2+2)(x^2+4)+2x(x^2+2)这步怎么来的？ 还有a^5+a^4+a^3+2a^2+2a+2,帮帮忙啦