Sequence And Series Question 593
Question: The $ 20^{th} $ term of the series $ 2\times 4+4\times 6+6\times 8+……. $ will be
[Pb. CET 1988]
Options:
A) 1600
B) 1680
C) 420
D) 840
Show Answer
Answer:
Correct Answer: B
Solution:
The given series $ 2\times 4+4\times 6+6\times 8…. $ $ n^{th} $ terms $ T_{n}=2n\ .\ 2(n+1)=4n(n+1) $ Putting $ n=20 $ , we get $ T_{20}=4\ .\ 20(20+1)=1680 $ .
BETA
