用计算机咯,你还想口算、笔算?
a^x=b*c^x
x=log(a,b*c^x)
=log(a,b)+log(a,c^x)
=log(a,b)+xlog(a,c)
x=log(a,b)/(1-log(a,c))
=log(a/c,b)
=lgb/lg(a/c)
x=6.4379415221176976877757064482095
你可以代进去验算一下