Binomial Theorem And Its Simple Applications Question 72

Question: $ ( \begin{matrix} n \\ 0 \\ \end{matrix} )+2,( \begin{matrix} n \\ 1 \\ \end{matrix} )+2^{2}( \begin{matrix} n \\ 2 \\ \end{matrix} )+…..+2^{n}( \begin{matrix} n \\ n \\ \end{matrix} ) $ is equal to

[AMU 2000]

Options:

A) $ 2^{n} $

B) 0

C) $ 3^{n} $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

  • $ {{(1+x)}^{n}}={}^{n}C_0+x.{}^{n}C_1+x^{2}.{}^{n}C_2+….+x^{n}.{}^{n}C_{n} $ Put x = 2

therefore $ 3^{n}={}^{n}C_0+2.{}^{n}C_1+2^{2}.{}^{n}C_2+2^{3}.{}^{n}C_3+….+2^{n}{{.}^{n}}C_{n} $ .