已知X+Y+Z=3 求证(X^2+Y^2)/(2+X^2+Y^2)+(.)+(.)>=3/2

已知x,y,z 大于0,x+y+z=2,求证 xz/y(y+z)+zy/x(x+y)+yx/z(z+x)大于等于2/3 已知x,y,z都是正数,且xyz=1,求证：x^2/(y+z)+y^2/(x+z)+z^2/(x+y)≥3/2 试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 求证x^8+y^8+z^8>=x^3y^2z^2+x^2y^3z^2+x^2y^2z^3 已知x^2+y^2+z^2=1,求证x+y+z-2xyz 已知三个实数x,y,z满足条件(z-x)^2-4(x-y)(y-z)=0,求证:x,y,z成等差数列 已知x,y,z都是正数,且3^x=4^y=6^z 求证 1/z-1/x=1/2y 已知3x=4y,2y=5z,试求x:y:z 已知2x次方=3 2y次方=5 2z次方=15,求证：x+y+z 已知3x+4y+5z=1求证X^2+y^2+z^2大于等于1/50 已知3x-2y-5z=0,2x-5y+4z=0,且x,y,z均不为0,求3x*x+2y*y+5z*z/5x*x+y*y- 已知2^x=3^y=6^z≠1,求证:1/x+1/y=1/z