Binomial Theorem And Its Simple Applications Question 46
Question: The coefficient of $ x^{5} $ in $ {{(1+2x+3x^{2}+…)}^{-3/2}} $ is $ ( | x |<1 ) $
Options:
A) 21
B) 25
C) 26
D) none of these
Show Answer
Answer:
Correct Answer: D
Solution:
- [d] $ {{(1+2x+3x^{2}+…)}^{-3/2}}={{[{{(1-x)}^{-2}}]}^{-3/2}} $
$ ={{(1-x)}^{3}}=1-3x+3x^{2}-x^{3} $ Therefore, coefficient of $ x^{5} $ is 0.
BETA
