Question

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

• A. – 2
• B. – 1
• C. 2
• D. 1

Answer 1

Answer: (C)

2

Answer 2

We know that, $m_{1} + m_{2} = \frac{- 2h}{b}$and $m_{1}m_{2} = \frac{a}{b}$.

Given, $m_{1} + m_{2} = 4m_{1}m_{2}$ $\Rightarrow$ $\frac{- 2c}{7} = 4\left( \frac{1}{- 7} \right)$⇒ $c = 2$