若4x^2+4xy+2y^2-6y+9=0,试求（x^2+2y^2+3）（x^2+2y^2-3）-（x-2y）^2（x+2y）^2

若x+y=4,x-y=6,求xy(y^2+y)-y^2(xy+2x)-3xy的值. 1-2/x+y=xy,4y+6x=xy.求xy的解? 若x+y=4 x-y=6 求xy(x^2+y)-y^2(xy+2x)-3xy的值求值 2x^+xy-y^-4x+5y-6=? 若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=若2x^2-6xy+9y^2-4x+4=0,则y/x-x/y=? 诺x+y=6,xy=4 求(5x-4y-3xy)-(8x-y+2xy) 若x-y=4,xy=1,求(-2xy+2x+3y)-(3xy+2y-2x)-(x+4y+xy)的值 若x-y=4,xy=1,则(2x+y-2xy)-(3x+2y+xy)-(4xy+3y-5x)= x^+2xy+y^+4=16 x^-2xy+y^=16 求(3xy+6y^)+|x^-(2xy+2y^-3x^)|的值 x^2-4xy+5y^2+6y+9=0,x+y= 2(x*x-3xy-2y*y+2)- =-4y*y-6xy+3x 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 因式分解 x-xy+3y-3x 2x+xy-y-4x+5y-6 化简求值x-4y/2x-7xy+3y×x-2xy-3y/2x+3xy-2y÷3x-6y/4x-4xy+y,其中：x=1999,y=-1 4xy-[(x²+5xy-y²)-(3xy-1/2y)]x=3,y=-6 已知1/x-1/y=2,求3x+7xy-3y/2x-3xy-2y答案是1/x-1/y=2(y-x)/xy=2 得：x-y=-2xy(3x+7xy-3y)/(2x-3xy-2y)=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy)=xy/(-7xy)=-1/7 谁能帮我解释一下=[3(x-y)+7xy]/[2(x-y)-3xy]=(-6xy+7xy)/(-4xy-3xy) 是怎 若3x^2+xy-2y^2=0,求（x+y/x-y+4xy/y^2-x^2)除以(x^2+2xy-3y^2/x^2-9y^2)的值 已知x^2+9y^2-2x-6y+2=0,求{-（xy/（x-y）^2}^4*(y^2-xy/x)^3*x^4/y^10/(x/xy-y^2)^5的值