-a^3+a^2+2a=?因式分解 16（x-y）^2-9(x+y)^2=( )*( ) (a+b)^3-(a+b)=(a+b)*( )*( ) 因式分解

-a^3+a^2+2a=-a(a^2-a-2)=-(a-2)(a+1)16（x-y）^2-9(x+y)^2=[4(x-y)]^2-[3(x+y)]^2=[4(x-y )+3(x+y )][4(x-y)-3(x+y)]=(4x-4y+3x+3y)(4x-4y-3x-3y)=(7x-y)(x-7y)(a+b)^3-(a+b)=(a+b)(a^2-ab+b^2)-(a+b)=(a+b)(a^2-ab...