x/(1+x)+y/(1+y)+z/(1+z)=1 求证x+y+z大于等于2(xy+yz+zx)

1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) 已知 x/(y+z)+y/(z+x)+z/(x+y)=1求 (x*x)/(y+z)+(y*y)/(x+z)+(z*z)/(x+y)=? 分解因式：（1):x(x-y)+y(y-X) 多项式(x+y-z)(x-y+z)-(y+z-X)(Z-x-y)的公因式是多少? X>Y>Z,试确定1/(X-Y)+1/(Y-Z)+1/(Z-X)的符号 {x+y-z=11 y+z-x=5 z+x-y=1 {x+y-z=11,x-y-z=-5,x-y+z=1 若1/X 1/y 1/z 成等差数列,求证:(Y-Z-X)/X (Z+X-Y)/Y (X+Y-Z)/z也成等差数列越快越好 X/Y+Z=Y/X+Z+1=Z/X+Y-1=X+Y+Z,求x+y+z等于多少 计算x/y+x=y/x+z+1=z/x+y-1的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 已知实数x y z满足x/(x+1)=y/(y+2)=z/(z+3)=(x+y+z)/3,求x+y+z的值 分式加减的几道题目求速度1 .(x+y)²/（x-z)(y-z) - (y+z)²/（x-z)(y-z) = 2.2x+3y/x-y+2y/y-x-3y/x-y= (x+y+z)÷10=x+1.1 y+x=z-80+y-1 z-y=8x+y+8 x+z÷y=? 已知实数X.Y.Z满足(Y+Z)分之X+(Z+X)分之Y+(X+Y)分之Z=1,则(Y+Z)分之X平方+(Z+X)分之Y平方+(X+Y)分之Z平方的值为（ ） 有谁能帮俺解释一下++x||++y&&++z是什么意思啊?main(){int x,y,z (x,y,z);x=y=z=1; ++x||++y&&++z; printf(x=%d,y=%d,z=%d ,x,y,z) } x+y+z=6 x+2y+3z=14 y+1=z f(x,y,z)=In{[x^α+z^(1-α-β)]/y^β}+x/z+(z/x)^β,求 ∂f(x,y,z)/∂y X+2Y= -12X+Y+Z= 1-X+Y-Z= -1