求(x+y)(2x-y)-(x+2y)(x-2y)的值,其中x=3,y=4

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 化简y(x+y)+(x+y)(x-y)-x^2 (x+y)(x-y)-(x-y)^2如题 (x+y)(x-y)-(x-y)^2 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 因式分解x(x+y)(x-y)-x(x+y)^2 求(1+y)-2x(1+y)+x(1-y) y=2x*arctan(y/x),求y‘’ 求因式分解(x-y)²-2(x-y)³和（x+y）（x-y）-x（x-y） 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 x+2y=2x+y+1=7x-y 求：2x-y? 求做因式分解12(x+y)^2+11(x+y)(x-y)+2(x-y)^2 f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! f(x+y,y/x)=x^2-y^2求f(x,y) x^2+y^2=15,x+y=7,x＞y,求x-y