求y=[(x+5)(x+2)]/(x+1)(x大于等于1)的值域

(x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 求y=(5x-1)/(4x+2) (x 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 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 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 x+2y=2x+y+1=7x-y 求：2x-y? 求(X+Y)(X-Y)(X²+Y²),X=5 Y=2, 若x*x+y*y=x+y-1/2,求x,y的值如题 x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2 y=(2x*x-2x+3)/(x*x-x+1),求值域? 4x-3y=5 x^2+y^2=1 求x,y 3x+4y-5=0 x^2+y^2=1求x.y x^2-x+y^2+2y+5/4=0 求x^-1+y^0 x+y=8 2x-y=1 求3x+5y 已知x>0,y>0,2/x+5/y=1,求x+y最小值 已知:2x-y/x+y=1/5,求2x+5y/6x-2y的值 已知x+y=-1,xy=-2,求代数式-5（x+y)+(x-y)+x(xy+y)的值