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JEE Main 202125 JulyEvening Shift
Exam
JEE Main
Year
2021
Date
25 July
Shift
Evening Shift
Subject
Mathematics
Chapter
Binomial Theorem

JEE Main 2021 · 25 July · Evening Shift · Mathematics · Binomial Theorem

If the co-efficient of x ^ 7 and x ^ 8 in the expansion of (2 +...

If the co-efficient of x7and{x}^{7} and{x}^{8} in the expansion of (2+x3)nareequal,thenthevalueof{\left(2 + \dfrac{x}{3}\right)}^{n} are equal, then the value ofn is equal to :

Correct answer

0

Step-by-step solution

We have, the co-efficient of x7and{x}^{7} and{x}^{8} in the expansion of (2+x3)nareequal.<p>Therefore,{\left(2 + \dfrac{x}{3}\right)}^{n} are equal.<p>Therefore,C7 n {2}^{n - 7}\dfrac{1}{{3}^{7}} = C8 n {2}^{n - 8}\dfrac{1}{{3}^{8}}</p><p></p><p>⇒ n - 7 = 48</p><p></p><p>⇒ n = 55 .

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