QJEEM21Ma6ce2: JEE Main 2021 Mathematics - Class 11 JEEM21Ma6ce2 Solution: If the co-efficient of x 7 and x 8 in the expansion of are…

Question

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If the co-efficient of x⁷ and x⁸ in the expansion of

{\left( {2 + {x \over 3}} \right)^n}

are equal, then the value of n is equal to _____________.

Accepted Answer

{}^n{C_7}{2^{n - 7}}{1 \over {{3^7}}} = {}^n{C_8}{2^{n - 8}}{1 \over {{3^8}}}

\Rightarrow

n

-

7 = 48

\Rightarrow

n = 55

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