Binomial Theorem And Its Simple Applications Question 135
Question: Sum of 1+2+ $ 2^{2} $ + $ {2^{n-1}} $ is
Options:
A) $ 2^{n} $
B) $ 2^{n}+1 $
C) $ 2^{n}-1 $
D) $ {2^{n-1}} $
Show Answer
Answer:
Correct Answer: C
Solution:
- [c] put n=1 in the given alternatives. All the expressions other than (3) give a value greater then 1. or It is a G.P.S $ S_{n}=\frac{a(r^{n}-1)}{(r-1)}=\frac{1(2^{n}-1)}{(2-1)}=2^{n}-1. $
BETA
