Quantitative Aptitude Ques 1263

Question: The simplified value of $ (\sqrt{6}+\sqrt{10}-\sqrt{21}-\sqrt{35}) $ $ (\sqrt{6}-\sqrt{10}+\sqrt{21}-\sqrt{35}) $ is

Options:

A) 13

B) 12

C) 11

D) 10

Show Answer

Answer:

Correct Answer: D

Solution:

  • $ (\sqrt{6}+\sqrt{10}-\sqrt{21}-\sqrt{35})(\sqrt{6}-\sqrt{10}+\sqrt{21}-\sqrt{36}) $ $ ={(\sqrt{6}-\sqrt{35}+(\sqrt{10}-\sqrt{21})} $ $ {(\sqrt{6}-\sqrt{35})-(\sqrt{10}-\sqrt{21})} $ $ ={{(\sqrt{6}-\sqrt{35})}^{2}}-{{(\sqrt{10}-\sqrt{21})}^{2}}=(6+35-2\sqrt{6}\cdot \sqrt{35}) $ $ -(10+21-2\sqrt{10}\cdot \sqrt{21}) $ $ =41-2\sqrt{210}-31+2\sqrt{210}=41-31=10 $