If a, b, c are in G.P., prove that log a, log b, log c are in A.P.
Here,
a, b, c are in G.P>
b2=ac .........(i)
Now taking log or both the sides
⇒log(b)2=log ac
⇒2 log b=log a+logc
⇒log b−log a=log c−log b
Thus, log a, log b, log c are in A.P.