Sequence And Series Question 604
Question: If the nth term of geometric progression $ 5,-\frac{5}{2},\frac{5}{4},-\frac{5}{8},… $ is $ \frac{5}{1024} $ , then the value of n is
[Kerala (Engg.) 2002]
Options:
A) 11
B) 10
C) 9
D) 4
Show Answer
Answer:
Correct Answer: A
Solution:
$ \frac{448r-7}{r-1}=889 $
Þ $ \frac{b}{a},\frac{c}{b},\frac{a}{c} $
Þ $ {{( \frac{-1}{2} )}^{10}}={{( \frac{-1}{2} )}^{n-1}} $
Þ $ 10=n-1 $
Þ $ n=11 $ .
BETA
