Sequence And Series Question 184

Question: If the arithmetic, geometric and harmonic means between two positive real numbers be $ A,\ G $ and $ H $ , then

[AMU 1979, 1982; MP PET 1993]

Options:

A) $ A^{2}=GH $

B) $ H^{2}=AG $

C) $ G=AH $

D) $ G^{2}=AH $

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Answer:

Correct Answer: D

Solution:

Let $ A=\frac{a+b}{2},\ G=\sqrt{ab} $ and $ H=\frac{2ab}{a+b} $ . Then $ G^{2}=ab $ …..(i) and $ AH=( \frac{a+b}{2} )\ .\ \frac{2ab}{a+b}=ab $ …..(ii) From (i) and (ii), we have $ G^{2}=AH $ .