lga^(2a)=2alga
lgb^(2b)=2blgb
lgc^(2c)=2clgc
lga^(b+c)=(b+c)lga
lgb^(c+a)=(c+a)lgb
lgc^(a+b)=(a+b)lgc
f(x)=lgx是增函数
a>b>c>0
∵2alga>2blgb>2clgc
∴a^(2a)>b^(2b)>c^(2c).(1)
∵2a>b+c,2alga>(b+c)lga
∴a^(2a)>a^(b+c).(2)
∵a+b>2c,(a+b)lgc>2clgc
∴c^(a+b)>c^(2c).(3)
∵[(c+a)lgb]/(2alga)=(c+a)/(2a)*lgb/lga<1
∴a^(2a)>b^(a+c).(4)
∵[(c+a)lgb]/(2clgc)=(c+a)/(2c)*lgb/lgc>1
∴c^(2c)<b^(a+c).(5)
根据(1)(2)(3)(4)(5):
a^(2a)最大,c^(2c)最小