1. ## Simple vector problem

1) given OP = (4, -2, 1) and OQ = (2, 4, 4) Find PQ.

I think I got this right, I got PQ = (6, 2, 5) with magnitude (65)^0.5 ??

2) given OP = (7, -2, 3) and PQ = (0, 3, -4), find OQ

I got OQ = (7, 5, -7)

3) point P = (1, 2, 3), find points R and Q such that a = PQ and b=PR and obtain the vector QR

I would appreciate someones input/help on this as I'm not entirely sure how to do it

2. Deleted

3. Originally Posted by a8281333
1) given OP = (4, -2, 1) and OQ = (2, 4, 4) Find PQ.

I think I got this right, I got PQ = (6, 2, 5) with magnitude (65)^0.5 ??
NO. If you draw a picture you will see that you can "follow the arrows" from O to P (using vector OP) then from P to Q (using vector PQ. That is the same as saying that OQ= OP+ PQ. PQ= OQ-OP. Subtract, don't add.

2) given OP = (7, -2, 3) and PQ = (0, 3, -4), find OQ
I got OQ = (7, 5, -7)
Same basic argument: OQ= OP+ PQ so now you add rather than subtract.

3) point P = (1, 2, 3), find points R and Q such that a = PQ and b=PR and obtain the vector QR

I would appreciate someones input/help on this as I'm not entirely sure how to do it
You are given the single point P. Are you not given a and b? If so, just choose R and Q to be any points you want! Then PQ+ QR= PR so QR= PR- PQ= b- a.

4. sorry, a = 3i + j - k and b = -2i + 3j

i got for 1) (-2,6,3) and |PQ| = 7 which made sense when i drew the diagram

for 2) i got (7,1,-1)