y=2x+8,y=-6+4x,y=-x+8,y=4x哪一个是y随x的增大而减少的函数是

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 已知x.x+y.y+8x+6y+25=0,求代数式(x.x-4y.y)/(x.x+4xy+4y.y)-x/(x+2y)的值 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= x*x+2x-y*y+6y-8=0,x+y不等于2,求x-y的值 (x-4y)(2x+y)= {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 3(2X+Y)+(2(2x-Y)=6 (8X+4y)-(10X-5Y)=2 解方程组 x-y/3-x+y/4=2 x-y/6-x+y/8=3 解方程组8/(x+y) +(x-y)/2=3,6/(x+y)-(x-y)/4=1