The coefficient of 5th,6th,7th term are in the a.p in the expansion of

1.	The coefficient of 5th,6th,7th term are in the a.p in the expansion of (1+x)power n.\xa0
Answer» In the expension of (1+X)n, T(r+1)\xa0=\xa0nCr\xa0XrCofficient of (r+1)th term = nCrSo Cofficient of 5th, 6th and 7th term ll be\xa0nC4\xa0nC5\xa0nC6 respectivily\xa0As it is given these terms are in APSo, 2 * (\xa0nC5 ) =\xa0nC4\xa0+\xa0nC6(2 * n! ) / { (n-5)! 5!} = (n! ) / { (n-4)! 4!} + (n! ) / { (n-6)! 6!}i think you can proceed from here .\xa0\xa0

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