x/3=y/4,求(x*x-xy)/(x*x+y*y)的值

x/3=y/4,求(x*x-xy)/(x*x+y*y)的值 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 求（3x^+y^-5xy）-【2x^-（-4xy-y^+7x^）】=? 当x-y=2xy时,求4x-3xy-4y/xy x+y=2 xy=3/4求x, 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 已知x-y=4xy,求2x+3xy-2y/x-2xy-y的值 x-y=4xy,试求2x+3xy-2y/x-2xy-y 已知x-y=3xy,求5x+2xy-5y/x-4xy-y的值 已知x-y=4xy,求x-2xy-y分之2x+3xy-2y的值! x-y=4xy,试求2x+3xy-2y/x-2xy-y 已知x-y=3,xy=1,求（-2x+2x+3y)-(3xy+2y-2x)-(x+4y+xy) x(x-7x)=4x(y-xy)求y关于x的函数关系式 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 已知（x+2）^2+|x+y+5|=0,求3x^2y-[2x^2y-(2xy-x^2y)-4x^2]-xy 已知：（x+2)²+|x+y-2|=0,求3x²y+{-2x²y-[-2xy+(x²y-4x²）]-xy} x-y=1,xy=2.求：(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 .已知:x-y=1,xy=-2.求:(-2xy+2 x+3y)-(3xy+2y-2x)-(x+4y+xy)的值