Pair Of Straight Lines Question 37
Question: The gradient of one of the lines $ x^{2}+hxy+2y^{2}=0 $ is twice that of the other, then h =
[MP PET 1996]
Options:
A) $ \pm 3 $
B) $ \pm \frac{3}{2} $
C) $ \pm 2 $
D) $ \pm 1 $
Show Answer
Answer:
Correct Answer: A
Solution:
Applying the condition, $ 4\lambda h^{2}=ab{{(1+\lambda )}^{2}} $
Here $ \lambda =2 $ , therefore $ 4\times 2\times {{( \frac{h}{2} )}^{2}}=1\times 2{{(1+2)}^{2}}\Rightarrow h^{2}=9\Rightarrow h=\pm 3 $ .
BETA
