The equation of a line passing through the points (0,0,0) and (5,1,2) is:
[tex] \frac{x-0}{5-0} = \frac{y-0}{1-0} = \frac{z-0}{2-0} [/tex];
[tex] \frac{x}{5} = \frac{y}{1} = \frac{z}{2} [/tex].
Take [tex] \frac{y}{1} =t[/tex], then [tex] \frac{x}{5}=t \\ \frac{y}{1}=t \\ \frac{z}{2}=t \\ [/tex] [tex]\rightarrow [/tex] [tex]x=5t \\ y=t \\ z=2t \\ [/tex].
This is parametrical equation of a straight line, where [tex]y|_{t=0}=0 \\ y|_{t=1}=1[/tex].
