Binomial Theorem And Its Simple Applications Question 76
Question: $ C_1+2C_2+3C_3+4C_4+….+nC_{n}= $
[RPET 1995; MP PET 2002; Orissa JEE 2005]
Options:
A) $ 2^{n} $
B) $ n.2^{n} $
C) $ n.{2^{n-1}} $
D) $ n.{2^{n+1}} $
Show Answer
Answer:
Correct Answer: C
Solution:
- Trick: Put $ n=1,2,3,…. $
$ S_1=1,S_2=2+2=4 $ Now by alternate (c), put $ n=1,2 $
$ S_1={{1.2}^{0}}=1,S_2={{2.2}^{1}}=2.2 $
BETA
