x²-xy-2y²+2x-y+1=x²+2x+1-xy-y-2y²
=(x+1)²-y(x+1)-2y²
=(x+1)²-y²-y(x+1)-y²
=[(x+1)-y]*[(x+1)+y]-y[(x+1)+y]
=(x-y+1)(x+y+1)-y(x+y+1)
=(x+y+1)[(x-y+1)-y]
=(x+y+1)(x-2y+1)

祝你開心!希望能幫到你,如果不懂,請追問,祝學(xué)習(xí)進(jìn)步!O(∩_∩)O