对数计算
设log83=p,log35=q,则lg5=?
人气：269 ℃ 时间：2020-01-30 06:37:23
解答
用换底公式
p=lg3/lg8=lg3/3lg2
lg2=lg3/(3p)
q=lg5/lg3
lg3=lg5/q
代入lg2=lg3/(3p)
lg2=lg5/(3pq)
lg2=1-lg5
所以1-lg5=lg5/(3pq)
lg5=1/[1+1/(3pq)]=3pq/(3pq+1)
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