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If \(\dfrac{1}{b-a}+\dfrac{1}{b-c}=\dfrac{2}{b}\), then \(a, b\) and \(c\) are in

This question was previously asked in
NDA 2 2026 GAT Question Paper (13-Sep-2026)
The correct answer is

HP

Simplifying \(\dfrac{1}{b-a}+\dfrac{1}{b-c}=\dfrac{2}{b}\) leads to \(ab+bc=2ac\), which on dividing by \(abc\) gives \(\dfrac{1}{c}+\dfrac{1}{a}=\dfrac{2}{b}\). Thus \(\dfrac{1}{a}, \dfrac{1}{b}, \dfrac{1}{c}\) are in AP, so \(a, b, c\) are in HP.

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Similar Questions

  1. If H is the Harmonic Mean of three numbers 10C410C5, and 10C6, then what is the value of \(\frac{270}{H}\) ?

  2. If the roots of the equation a (b - c) x 2+ b (c - a) x + c (a - b) = 0 are equal, then which one of the following is correct?

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Important Questions from Harmonic Progressions

  1. The nth terms of the two series 3 + 10 + 17 + ... and 63 + 65 + 67 + .... are equal, then the value of n is:

  2. The value of n, for which \(\dfrac{a^{n+1} + b^{n+1}}{a^n+b^n}\) is the harmonic mean of a and b, is

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