(1)(x+1)^2(x-1)+2(x+1)(x-1)^2(2)-1/9a^2+25(3)-4x^2-12x-9(6)2x^3-8x(7)81-x^4

题目

(1)(x+1)^2(x-1)+2(x+1)(x-1)^2(2)-1/9a^2+25(3)-4x^2-12x-9(6)2x^3-8x(7)81-x^4
(8)(x-1)^2-4y^2(9)2-8(x+2)^2

答案

(x+1)^2(x-1)+2(x+1)(x-1)^2=(x+1)(x-1)[(x+1)+2(x-1)^2]=(x+1)(x-1)(x+1+2x-2)=(x+1)(x-1)(3x-1)-1/9a^2+25=25-1/9a^2=(5+1/3a)(5-1/3a)-4x^2-12x-9=-(4x^2+12x+9)=-(2x+3)^22x^3-8x=2x(x^2-4)=2x(x+2)(x-2)81-x^4=...