Q. The points (1, 1), $( - 5,\ 5)$ and (13, λ) lie on the same straight line, if λ is equal to
A) 7
B) $- 7$
C) $\pm 7$
D) $0$
Explanation
(b)
The equation of any line passing through (1, 1) and $( - 5,\ 5)$ is
$y - 1 = \frac{5 - 1}{- 5 - 1}(x - 1)$
$\Rightarrow \ - 6(y - 1) = 4(x - 1)$
Since, the point $(13,\lambda)$ lies on this line.
$\therefore\ - 6(\lambda - 1) = 4(13 - 1)\ \Rightarrow \ \lambda = - 7$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.