RRB Technician 2014 Ques 14
Question: If x and y are positive with $ x-y=2 $ and $ xy=24, $ then $ \frac{1}{x}+\frac{1}{y} $ is equal to
Options:
A) $ \frac{5}{12} $
B) $ \frac{1}{12} $
C) $ \frac{1}{6} $
D) $ \frac{25}{6} $
Show Answer
Answer:
Correct Answer: A
Solution:
- $ \because $ $ x-y=2 $ and $ xy=24 $
$ \therefore $ $ {{(x+y)}^{2}}={{(x-y)}^{2}}+4xy $ $ ={{(2)}^{2}}+4(24)=4+96=100 $
$ \therefore $ $ x+y=10 $ $ \frac{1}{x}+\frac{1}{y}=\frac{y+x}{xy}=\frac{10}{24}=\frac{5}{12} $
BETA
