杭州交通信息网libjingle:高一对数题急需谢谢
来源：百度文库 编辑：杭州交通信息网 时间：2024/05/05 18:42:04
若log[a]b*log[3]a=5，求b
log[a]b=lgb/lga
-->log[a]b*log[3]a=5
= lgb/lga * lga/lg3
= lgb/lg3=5
lgb=5lg3
b=3^5
..............................lgb*lga
log[a]b*log[3]a=------------------------
..............................lga*lg3
...........................lgb
.................=------------------------=5
...........................lg3
lgb=5lg3=lg(3^5)
b=3^5=243
log[a]b=lnb/lna
log[3]a=lna/ln3
所以lnb/ln3=5
b=3的5次方