Question

If p, q and r are three points with coordinates $(1,4)$ and $(4,5)$ and $(m,m)$ respectively, are collinear then value of $2m$ is

Answer 1

Given,

$(1,4),(4,5),(m,m)$ coodinates

$\Rightarrow \frac{m-1}{m-4}=\frac{5-m}{4-m}$

$(m-1)(4-m)=(5-m)(m-4)$

$5m-m^2-4=9m-m^2-20$

$-4m=-16$

$\therefore m=4$

$2m=8$