若xy∈R+ x+y=2 求证1/x+1/y≥2

若xy∈R+ x+y=2 求证1/x+1/y≥2 若xy∈R+ x+y=2 求证1/x+1/y≥2 已知x,y,z∈R,求证:x^2+y^2>=xy+x+y-1 已知x,y∈R,求证:x^2+y^2≥xy+x+y-1 已知x,y∈R,求证x2-xy+y2>=x+y-1 已知x,y属于正R,且x+2y=1,求证xy= 已知x,y属于 R +,且x+2y=1,求证 xy |x|>1,|y|>1,x,y∈R,求证|（x-y）/（1-xy）| 已知x,y∈R,求证:x+y+1≥x+y+xy 已知x,y∈R,求证:x-xy+y≥x+y-1 已知X,Y∈R+,且X+Y=1,求证：XY+1/XY≥17/4 已知X,Y∈R+,且X+Y=1,求证：XY+1/XY≥17/4hgfhg 若x.y属于R,且满足（X*X+Y*Y+2）（X*X+Y*Y-1）-18≤0.求证：XY≤2 已知x.y∈R,求证x2+y2+1≥x+y+xy 已知a,b∈R+,且x+y=1,求证:xy≤1/4 若x、y∈R+ x+y=2 D.1/(xy)>=1 已知函数f(x)对一切x,y∈R,都有f(x)+f(y)=f((x+y)/(1+xy)),求证f(x)为奇函数RT 若x,y属于R正,求证：x平方+y平方+1大于等于xy+x+y