You can express a line in 2D with one equation. However, to express

can you give an example for what yluean be equation incthose dimensions?

{(x,y,z) | y=0 and z=0}

specifies a line in 3 dim

>>8627001
You don't need three.

>>8627031
>yluean

>>8627001
You can express a line in 3D with 2 equations. Choose any y=f(x), then say z=c or even z=x.

>>8627001
A line which goes through points (a,b,c) and (d,e,f) can be expressed as

(x-1)/(1-d/a) = (y-1)/(1-e/b) = (z-1)/(1-f/c)

if a != d, b != e, and c != f

otherwise x = a, y = b, and/or z = c as appropriate.

In other words,

z = 1+(y-1)(1-f/c)/(1-e/b)
y = 1+(x-1)(1-e/b)/(1-d/a)

>>8627075
Meant to say

z = 1+(x-1)(1-f/c)/(1-d/a)
y = 1+(x-1)(1-e/b)/(1-d/a)

But same thing really.