放缩!不等式放缩法的极品难题!若x,y,z,a,b,c,r>0,证明:(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)>(x+z+a+c)/(x+z+a+b+c+r)字母没错放心做吧

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放缩!不等式放缩法的极品难题!若x,y,z,a,b,c,r>0,证明:(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)>(x+z+a+c)/(x+z+a+

放缩!不等式放缩法的极品难题!若x,y,z,a,b,c,r>0,证明:(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)>(x+z+a+c)/(x+z+a+b+c+r)字母没错放心做吧
放缩!不等式放缩法的极品难题!
若x,y,z,a,b,c,r>0,证明:
(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)
>(x+z+a+c)/(x+z+a+b+c+r)
字母没错
放心做吧

放缩!不等式放缩法的极品难题!若x,y,z,a,b,c,r>0,证明:(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)>(x+z+a+c)/(x+z+a+b+c+r)字母没错放心做吧
这个不等式不强.放缩两次仍成立.
证明:
(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)
>(x+y+a+b)/(x+y+z+2a+b+c+r)+(y+z+b+c)/(x+y+z+2a+b+c+r)
=(x+2y+z+a+2b+c)/(x+y+z+2a+b+c+r)
>(x+y+z+a+b+c)/(x+y+z+2a+b+c+r)
注意到有如下结论当:x,y,t>0,且xx/y.
这个很好证明,上式交叉乘开化简可得y>x显然成立.于是上述结论正确.
所以:
(x+y+z+a+b+c)/(x+y+z+a+b+c+r)>(x+z+b+c)/(x+z+a+b+c+r){注:分子分母同时减去y+a}
于是(x+y+a+b)/(x+y+a+b+c+r)+(y+z+b+c)/(y+z+a+b+c+r)>(x+z+b+c)/(x+z+a+b+c+r)成立.