Binomial Theorem And Its Simple Applications Question 208
Question: The coefficient of $ a^{3}b^{4}c $ in the expansion of $ {{(1+a-b+c)}^{9}} $ is equal to
Options:
A) $ \frac{9!}{3!6!} $
B) $ \frac{9!}{4!5!} $
C) $ \frac{9!}{3!5!} $
D) $ \frac{9!}{3!4!} $
Show Answer
Answer:
Correct Answer: D
Solution:
- [d] $ {{(1+a-b+c)}^{9}} $
$ =\sum{\frac{9!}{x_1!x_2!x_3!x_4!}.{{(1)}^{x1}}{{(a)}^{x2}}{{(-b)}^{x3}}{{(x)}^{x4}}} $
$ \Rightarrow $ Coefficient of $ a^{3}b^{4}c=\frac{9!}{1!3!4!1!}=\frac{9!}{3!4!} $
BETA
