1.

If in a HP, a5 = 7 and a7 = 5, then what will be the value of a12?1. \(\frac{{28}}{{13}}\)2. \(\frac{{35}}{{12}}\)3. \(\frac{{37}}{{12}}\)4. \(\frac{{29}}{{12}}\)

Answer» Correct Answer - Option 2 : \(\frac{{35}}{{12}}\)

CONCEPT:

If in a Harmonic progression am = n and an = m, then am+n will be given as  \({a_{m + n}} = \frac{{mn}}{{m + n}}\) .

CALCULATIONS:

Given:

a5 = 7 and a7 = 5

So \({a_{12}} = {a_{5 + 7}} = \frac{{5 \times 7}}{{5 + 7}} = \frac{{35}}{{12}}\) 

Therefore, option (2) is the correct answer.



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