If xa = xb/2zb/2 = zc, then prove that are in A.P.

Take logs of each expression, using ln(xa) = a ln(x) etc


ln (p*q) = ln(p) + ln(q):


Given,


xa = xb/2zb/2 = zc


Taking log on each term –


…(1)


The equality of the first and third expressions tells us that


…(2)


The second expression is equal to



{using equation 1}



Divide through out by ln x


a = b/2 + ab/2c


2ac = bc + ab


Dividing the equation by abc –



From this are in GP.


18