Binomial Theorem And Its Simple Applications Question 180

Question: In the expansion of $ {{(1+x)}^{50}}, $ the sum of the coefficient of odd powers of x is

[UPSEAT 2001; Pb. CET 2004]

Options:

A) 0

B) $ 2^{49} $

C) $ 2^{50} $

D) $ 2^{51} $

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Answer:

Correct Answer: B

Solution:

  • We have, $ {{(1+x)}^{50}}=\sum\limits_{r=0}^{50}{{}^{50}C_{r}x^{r}} $ .

Therefore, sum of coefficients of odd power of x = $ {}^{50}C_1+{}^{50}C_3+…+{}^{50}C_{49} $ = $ \frac{1}{2}[{}^{50}C_0+{}^{50}C_1+…+{}^{50}C_{50}]=\frac{1}{2}[2^{50}]=2^{49} $ .