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If the sum of the slopes of the lines given by $x^2-2cxy-7y^2=0$ is four times their product c has the value.

$\begin{array}{1 1}(A)\;-2\\(B)\;-1 \\(C)\;2\\(D)\;1 \end{array}$

1 Answer

Let the lines be $y=m_1X$
$y=m_2x$ then
Given $m_1+m_2=4m_1m_2$
=> $ \large\frac{2c}{7}=\frac{-4}{7}$
Hence C is the correct answer.
answered Apr 8, 2014 by meena.p

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