# vectors question

Discussion in 'Mathematics' started by fudgesweets, Jun 20, 2011.

1. ### fudgesweetsNew commenter

Write: r=(i+j+k) +t(-3i+4j) in cartesian form

I have: (x-1) /-3 =(y-1)/4= (z-1)/0

Is it correct to have the k component to be divisible by zero? I woudnt have thought so. If not then how do you write the above in cartesian??

2. ### fudgesweetsNew commenter

its ok, i know now!

3. ### twentysix

Is this type of question still required? Edexcel at least no longer seem to be ask this nor is it in their recommended books- can anyone confirm or contradict that its off the edexcel syllabus?

4. ### bobboots

Forgive my ignorance, but is it possible to express a 3d line in cartesian form? I thought it had to be in vector form or parametric form (essentially the same) since something like 3x + 4y + 2z = 90 would be a plane.

5. ### Subjectknowledge

Writing r = xi + yj + zk, we see that
x = 1 - 3t
y = 1 + 4t
z = 1

So (x - 1)/-3 = (y - 1)/4 [ = t ] and z = 1
Or if you prefer, the line lies entirely in the z = 1 plane, with the 2 dimensional equation
y = -4x/3 + 7/3