Manipal MET2012MathematicsSequences and Series
If x 1, y 1, z 1 are in GP, then 1 1+ x 1 1+ y , 1 1+ z are in
Options
- AAP
- BHP
- CGP
- DNone of these
Correct answer
B. HP
Step-by-step solution
Let the common ratio of the GP be r . Then, y=x r and z=x r^2 . y= x+ r and z= x+2 r Putting A=1+ x, D= r Then, 1 1+ x = 1 A , aligned & 1 1+ y = 1 1+ x r = 1 1+ x+ r = 1 A+D & and 1 1+ z = 1 1+ x+2 r = 1 A+2 D aligned Here we see that A, A+D and A+2 D are in AP. 1 A , 1 A+D and 1 A+2 D are in HP. Therefore, 1 1+ x , 1 1+ y , 1 1+ z , are in HP.