If the co-efficient of x 7 and x 8 in the expansion of 2 + x 3 n are equal, then the value of n is equal to :

If the co-efficient of x7 and x8 in the expansion of 2+x3n are equal, then the value of n is equal to :

Solution

We have, the co-efficient of x7 and x8 in the expansion of 2+x3n are equal.

Therefore, C7n2n-7137=C8n2n-8138

⇒n-7=48

⇒n=55.

Asked in: JEE Main 2021 (25 Jul Shift 2)

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