If x>1,y>1,z>1 are in GP, then 11+ln x,11+ln y,11+ln z are in
HP
Let the common ratio of the GP be r. Then,
y=xr and z=xr2
⇒ln y=ln x+ln r and ln z=ln x+2 ln r
Let A=1+ln x, D=ln r
Then, 11+ln x=1A,11+ln y=11+ln x+ln r=1A+D
and 11+ln z=11+ln x+2 ln r=1A+2D
Therefore, 11+ln x,11+ln y,11+ln z are in HP