1.

If the sum of the slopes of the lines given by `4x^2+2lambdaxy-7y^2=4` is equal to the product of the slopes,then `lambda` is equal to?

Answer» Let we have below two lines that represent the given equation.
`y-m_1x = 0` and `y-m_2x=0`
Combined equation of these two lines will be,
`(y-m_1x)(y-m_2x) = 0`
`y^2-(m_1+m_2)xy+m_1m_2x^2=0->(1)`
Now, the given equation is,
`4x^2+2lambdaxy -7y^2= 4`
`y^2-4/7x^2- 2/7lambdaxy = 0`
Comparing this with the given equation (1),
`m_1+m_2 = 2/7lambda`
`m_1m_2 = -4/7`
As we are given sum and product of roots are equal. So,
`2/7lambda = -4/7=> lambda = -2`


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