Quantitative Aptitude Ques 2247
Question: If $ m-5n=2, $ then the value of $ (m^{3}-125n^{3}-30mn) $ is
Options:
A) 6
B) 7
C) 8
D) 9
Show Answer
Answer:
Correct Answer: C
Solution:
- Given, $ m-5n=2 $ … (i) On cubing both sides, we get $ {{(m-5n)}^{3}}={{(2)}^{3}} $
$ \Rightarrow $ $ m^{3}-125n^{3}-3(m)(5n)(m-5n)=8 $
$ \Rightarrow $ $ m^{3}-125n^{3}-15mn(2)=8 $ [from Eq, (i)]
$ \Rightarrow $ $ m^{3}-125n^{3}-30mn=8 $
BETA
