4x²+4xy+y²-4x-2y-3

3x²y+xy²-[2xy²-4x²y+（x²y-2xy²） (2x²y-3xy²)-3(x²y-2xy²)+2（x²y-4xy&# 计算 2xy[4x²y²-3y（xy+x²y）-xy²] (-x-2y)(x²-2xy+4y²) 化简(x²y-4y²)/(x²+4xy+4y²)*[(4xy)/(x-2y)+x 化简4xy-3y²-3x²+xy-3xy-2x²+x²-2y² -4x²y-8xy²+2x²y-3xy² 已知x/y=2,求2x(x+y)-y(x+y)/4x²-4xy+y² -3(xy-2x²)-[y²-(5xy-4x²)+2xy] A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²+3x-y,若x= 设A=2x²-3xy+y²-x+2y,B=4x²-6xy+2y²-3x-y,若x 1.化简：x²-4y²/x²+y²+2xy÷2y+x/x²+xy.