If logax,logbx,logcx\log_a x, \log_b x, \log_c xlogax,logbx,logcx are in a geometric progression, which of the following is true?
logxb2=logxa⋅logxc\log_x b^2 = \log_x a \cdot \log_x clogxb2=logxa⋅logxc
1logxb=1logxa+1logxc\frac{1}{\log_x b} = \frac{1}{\log_x a} + \frac{1}{\log_x c}logxb1=logxa1+logxc1
(logxb)2=logxa⋅logxc(\log_x b)^2 = \log_x a \cdot \log_x c(logxb)2=logxa⋅logxc
2lnb=lna+lnc2 \ln b = \ln a + \ln c2lnb=lna+lnc