求帮忙、因式分解、 6xy^2-9x^2y-y^3= ( a-b)^3(x-y)+(x+y)(a-b)^3= 25(m-n)^2-9b^2(m-n)^2=

问题描述:

求帮忙、因式分解、 6xy^2-9x^2y-y^3= ( a-b)^3(x-y)+(x+y)(a-b)^3= 25(m-n)^2-9b^2(m-n)^2=

6xy^2-9x^2y-y^3=-y(9x^2-6xy+y^2)=-y(3x-1)^2( a-b)^3(x-y)+(x+y)(a-b)^3=(a-b)^3(x-y+x+y)=2x(a-b)^325(m-n)^2-9b^2(m-n)^2=(m-n)^2(25-9b^2)=(m-n)^2(5+3b)(5-3b)