(1)x^n+2 -6x^2+n +8x^2
问题描述：
(1)x^n+2 -6x^2+n +8x^2
(2)x^2 -21xy +98y^2 +x -7y
(3)x^2 +6xy +9y^2 -4a^2 +4ab -b^2
答
(1)x^n+2 -6x^2+n +8x^2 =x^2(x^n-6x^n+8)=x^2(8-5x^n)(2)x^2 -21xy +98y^2 +x -7y =(x-7y)(x-14y)+(x-7y)=(x-7y)(x-14y+1)(3)x^2 +6xy +9y^2 -4a^2 +4ab -b^2=(x+3y)^2-(2a-b)^2=(x+3y+2a-b)(x+3y-2a+b)