Pair Of Straight Lines Question 43
Question: If the slope of one line of the pair of lines represented by $ ax^{2}+4xy+y^{2}=0 $ is 3 times the slope of the other line, then a is
[DCE 1999]
Options:
A) 1
B) 2
C) 3
D) 4
Show Answer
Answer:
Correct Answer: C
Solution:
Here $ m_1+m_2=-4 $ ….. (i)
and $ m_1m_2=a $ …(ii)
Given that $ m_1=3m_2 $ . By (i), $ 3m_2+m_2=-4 $
Therefore $ m_2=-1 $ Hence, $ m_1=-3 $ . Now, by (ii) $ a=3. $
BETA
