哦.
由已知可得：
log8(3)=lg3/lg8=lg3/(3lg2)=a,log3(5)=lg5/lg3=b
所以：[lg3/(3lg2)]×(lg5/lg3)=ab
即lg5/(3lg2)=ab
lg5=3ablg2
lg5=3ab(1-lg5)
lg5=3ab-3ablg5
(1+3ab)lg5=3ab
解得：lg5=3ab/(1+3ab)是lg5没错，算的就是lg5