f(lga)=a^(lga + 1/2)=√10=10^(1/2)
两边同时取对数：lga^(lga + 1/2)=lg10^(1/2)
(lga + 1/2)lga=(1/2)lg10
lg²a + (1/2)lga=1/2
整理后得：2lg²a + lga - 1=0
(2lga - 1)(lga + 1)=0
lga=1/2或lga=-1
则 a=√10或a=1/10
∵0