设啊,a,b,c均为实数,求证1/2a/2b/2c≥1/b+c +1/c+a +1/a+b

问题描述:

设啊,a,b,c均为实数,求证1/2a/2b/2c≥1/b+c +1/c+a +1/a+b

证明:∵(a-b)²≥0
(a+b)²≥4ab
∴1/4a+1/4b =(a+b)/4ab ≥(a+b)/(a+b)²即,1/4a+1/4b≥1/(a+b) (1)
同理 1/4a+1/4c≥1/(a+c) (2)
1/4b+1/4c≥1/(b+c) (3)
(1)+(2)+(3)得
1/2a+1/2b+1/2c≥1/(b+c)+1/(c+a)+1/(a+b)希望有帮到你!