(2X-Y)²-4(X-Y)*(X+Y)-(X-Y)*(X-1)

问题描述:

(2X-Y)²-4(X-Y)*(X+Y)-(X-Y)*(X-1)

(2X-Y)²-4(X-Y)*(X+Y)-(X-Y)*(X-1)
=4x²-4xy+y²-4x²+4y²-x²+xy-y+x
=-x²-4xy+5y²+xy-y+x