BITSAT 2014 Paper

For concurrency of 3 lines the determinant of coefficients of equations should be 0.
i.e. |

3	−4	−13
8	−11	−33
2	−3	λ

| = 0
⇒ 3(-11λ - 99)+4(8λ + 66) -13(-24 + 22) = 0
⇒ -33λ - 297 + 32λ + 264 + 312 - 286 = 0
⇒ - λ - 583+ 576 = 0 ⇒ λ = -7