Easy INTEGER +4 / -1 PYQ · JEE Mains 2021

The ratio of the coefficient of the middle term in the expansion of (1 + x)20 and the sum of the coefficients of two middle terms in expansion of (1 + x)19 is _____________.

Answer (integer) 1

Solution

Coeff. of middle term in (1 + x)<sup>20</sup> = ${}^{20}{C_{10}}$ &amp; Sum of coeff. of two middle terms in (1 + x)<sup>19</sup> = ${}^{19}{C_{9}}$ + ${}^{19}{C_{10}}$<br><br>So required ratio = $${{{}^{20}{C_{10}}} \over {^{19}{C_9}{ + ^{19}}{C_{10}}}} = {{^{20}{C_{10}}} \over {^{20}{C_{10}}}} = 1$$

About this question

Subject: Mathematics · Chapter: Binomial Theorem · Topic: Binomial Expansion

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