Sequence And Series Question 422
Question: If $ a $ be the arithmetic mean of $ b $ and $ c $ and $ G_1,\ G_2 $ be the two geometric means between them, then $ G_1^{3}+G_2^{3}= $
Options:
A) $ G_1G_2a $
B) $ 2G_1G_2a $
C) $ 3G_1G_2a $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
Trick: Put $ b=1 $ and $ c=8 $ so that $ a=4.5 $ and $ G_1=2,\ G_2=4 $ . Now $ G_1^{3}+G_2^{3}=72 $ . Also option (b) gives this value $ i.e. $ $ 2\times 2\times 4\times \frac{9}{2}=72 $ .
BETA
