[(x-y)²+y(4x-y)-4x]/2
=(x²+y²-2xy+4xy-y²-4x)/2
=(x²+2xy-4x)/2
=x(x+2y-4)/2
=4*(4+4026-4)/2
=2*4026
=8052
担心不显示平方符号,图片格式