题：x=1.96 ,y=2.56求x-2√xy+y/√x-√y （me有个疑问请往下看）答案：x=1.96 ,y=2.56则√x=1.4,√y=1.6x-2√xy+y/√x-√y=(√x-√y)²/(√x-√y)=√x-√y=1.4-1.6=-0.2为什么2√xy在下一步就没了呢

x=1.96 ,y=2.56求x-2√xy+y/√x-√y x=1.96 ,y=2.56求x-2√xy+y/√x-√y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 求y=(x^2)+2x(x≥0) y=-x+2x(x 如果|X|=4 |Y|=2 且|X+Y|=X+Y 求X+Y 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y x+2y=2x+y+1=7x-y 求：2x-y? x^2+y^2=15,x+y=7,x＞y,求x-y 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 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 求(X+Y)(X-Y)(X²+Y²),X=5 Y=2, y=3(x-y),x=2(x-y)求x,y的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² f(x+y,x-y)=(x^2-y^2)/2xy,求f(x,y)! 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 f(x+y,y/x)=x^2-y^2求f(x,y) 已知x≠y,x^2-x=y^2-y,求x+y的值. f(x+y,y/x)=x^2-y^2,求f(x,y),详见里面