$\sum_{r=1}^{15} r^2 \left( \frac{{}^{15}C_r}{{}^{15}C_{r-1}} \right) = $

  • A
    $560$
  • B
    $680$
  • C
    $840$
  • D
    $1020$

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Similar Questions

यदि ${S_n} = \sum\limits_{r = 0}^n {\frac{1}{{^n{C_r}}}} $ और ${t_n} = \sum\limits_{r = 0}^n {\frac{r}{{^n{C_r}}}} $ है,तो $\frac{{{t_n}}}{{{S_n}}}$ का मान क्या होगा?

यदि $(1+x+x^2)^n = a_0 + a_1 x + a_2 x^2 + \ldots + a_{2n} x^{2n}$ है,तो $a_0 + a_2 + a_4 + \ldots + a_{2n} =$

यदि $(1 + x)^n = C_0 + C_1x + C_2x^2 + .......... + C_nx^n$ है,तो $C_0^2 + C_1^2 + C_2^2 + C_3^2 + ...... + C_n^2$ =

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मान लीजिए $(1+2x)^{20} = a_0 + a_1x + a_2x^2 + \dots + a_{20}x^{20}$ है। तो $3a_0 + 2a_1 + 3a_2 + 2a_3 + 3a_4 + 2a_5 + \dots + 2a_{19} + 3a_{20}$ का मान ज्ञात कीजिए।

योगफल $\sum\limits_{i = 0}^m {\binom{10}{i}} {\binom{20}{m - i}}$,(जहाँ $\binom{p}{q} = 0$ यदि $p < q$),तब अधिकतम होता है जब $m$ है

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