(3x+2y)(9x²－6xy＋4y²﹚化简，求方法

x²-y²+6x+9分之x²+y²-9-2xy 6x²y-9xy-xy²+3x²y 计算或化简：[（x-y）/(x+3y)]÷[（x²-y²）/(x²+6xy+9y²)]-（2y）/x+y x/y=2,求分式x²-xy+3y²/x²+xy+6y² 分解因式：2x²-8xy+5y²6x²-9x-4242x²-85xy+42y²3x²-5xy-y²(2x-y+3)(2x-y+1)-15(x+y)²+4(x+y)(3x-y)+4(3x-y)²完全按照原题打的 -9x²-y²+6xy x²-2xy+y²-9 6x²-xy-15y²=0 求x²-2xy+4y²/2x²-3xy-3y²告诉下 6x²-xy-15y²=0 求2x²-3xy-3y²分之x²-2xy+4y² 因式分解：x²－3xy－10y² +x+9y+2 已知2x²+xy=10,3y²+2xy=6,求4x²+8xy+9y²的值 已知：x²-xy=1,4xy-3y²=-2,求x²-9xy+6y²-5的值 若x²+xy-2y²=0,则x²+3xy+y²/x²+y² x²+xy-2y²=0则x²+3xy+y²/x²+y² 6xy²-9x²y-y²因式分解 xy²/(x²y-y) × x²/(x²+x)=(x²-3x)/(x²-5x) × 2x-10/(x²-6x+9)=化简求植x²-1/(x²-x-2)除以x/2x-4,其中x=1/2[x-x/(x+1)]除以[x/(2x-4)] ,其中x=√2+1 单项式2xy,6x²y²,-3xy,-4x²y²的和为-------------- 求单项式2xy,6x² y²,-3xy,-4x²y²的和.