Q. 39 D5.0( 2 Votes )

# Find the two middle terms in the expansion of :

Answer :

For ,

a=3x, and n=9

As n is odd, there are two middle terms i.e.

I. and II.

General term t_{r+1} is given by,

I. The first middle term is

Therefore, for 5^{th} middle term, r=4

Therefore, the first middle term is

II. The second middle term is

Therefore, for the 6^{th} middle term, r=5

Therefore, the second middle term is

………

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