已知|3x-2y-39|+|5x+3y-84|=0,求4x+7y的平方根如上.急

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知x/5=y/3,则(x/x+y)+(y/x-y)-(yxy/xxx-yxy) 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x-y=3则5(x-y)-3x+3y-2= 已知x-y=3则5(x-y)-3x+3y-2= 已知2x-y=-3,求代数式5(x-3y)-2(x-7y) 已知3x-2y/x+y=5/3求x；y的值 已知x+y/3x-2y=5/3求x；y的值 已知5|x+y-3|+(x-2y)²=5,求x+y的值 已知4x=5y,那么(3x+y)/(x-2y)= 已知x,y>0 2x+y+3=xy 求5x+4y最小值 已知x,y满足约束条件 2x+5y>=10 2x-3y>=-6 2x+y 已知x,y满足约束条件{2x+5y>=10,2x-3y>=-6,2x+y 已知实数x,y满足2x+5y>=10;2x-3y>-6;2x+y 已知5/x=3/y,求x+y/x+x-y/y-x^2-y^2/y^2的值