The value of `lambda` for which the equation `x^2-y^2 - x - lambda y - 2 = 0` represent a pair of straight line, are

Options

A. `5//2`
B. `+-5`
C. `+-3`
D. `2//5`

Answer

C

Explanation

On comparing given equation with standard equation , we get , `a=1,b=-1,c=-2,h=0,g=-1//2,f=lambda//2`.
Given equation represent a pair of straight line ,if
`therefore abc+2fgh-af^2-bg^2-ch^2=0`
`rArr 1x -1x-2+0-(lambda^2)/(4)+(1)/(4)-0=0`
`rArr (lambda^2)/(4)=(9)/(4)rArr lambda=+-3`