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If the position vectors of three points are a-2b+3c, 2a+3b-4c-7b +10c, then he three points are
collinear
coplanar
non-collinear
neither
Let’s break this down, point by point.
- We have three position vectors:
P: a?–?2b?+?3c
Q: 2a?+?3b?–?4c
R: –7b?+?10c
- First, always check if they’re collinear. That means the vectors from one point to the others are proportional—basically, all the points line up on a single straight line.
- If not, then maybe they’re coplanar. That’s less restrictive: any three vectors in three-dimensional space (as long as they’re not all the same line) will always sit in some plane together.
- In fact, any three points in space will always be coplanar, because you can always draw a plane through three points.
- If you see the option “non-collinear,” that just means the vectors don’t line up but might be coplanar—so, not on a straight line, but sitting on the same flat surface.
- “Neither” would mean the points don’t even share a plane, but that can’t happen with only three points.
Let’s do a quick calculation:
Let’s check if vectors PQ and PR are proportional.
PQ = Q - P = (2a?+?3b?–?4c) – (a?–?2b?+?3c)
PQ = (2a – a) + (3b – (–2b)) + (–4c – 3c)
= a + 5b – 7c
PR = R – P = (–7b?+?10c) – (a?–?2b?+?3c)
= –a + (–7b – (–2b)) + (10c – 3c)
= –a – 5b + 7c
You can see that PR is exactly the negative of PQ. That means all three points fall on the same line. Collinear.
---
Option 1: Collinear
This is the correct answer. The vectors are proportional.
Option 2: Coplanar
This is always true for three points, but collinear is a stricter answer.
Option 3: Non-collinear
Nope, the vectors clearly are proportional, so they are absolutely collinear.
Option 4: Neither
Nope, not possible with three points.
By: Swaminath Yadav ProfileResourcesReport error
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