The Student Room Group

C4 Vector help

I am stuck on this question and can't see where I have gone wrong, the answer is 6i+8j+8k.

Here is the question:
The position vectors of the points A and B relative to the origin O are 3i+2J-k, 5i+6j+5k, respectively. Find the position vector of the point P which lies on AB produced such that AP=3BP

Here is my working out:
IMG_0007.JPG (3).jpg

In addition to this: What does it mean by P lies on AB produced?

Thanks

:smile:
Reply 1
Find the equation of the line AB and give express P (as it lies on AB) in terms the scalar parameter. Find the vector AP in terms of this scalar parameter and the vector BP and then I guess you can do it from there.
Reply 2
It means that if you join up the points A and B a straight line is produced.
Reply 3
P does not lie between A and B

It should be A , B and then P
Reply 4
The line passes through the points but does not stop at the points. It carries on infinitely.
Reply 5
Reply 6
Original post by the bear


Original post by MathMan
The line passes through the points but does not stop at the points. It carries on infinitely.


Original post by MathMan
It means that if you join up the points A and B a straight line is produced.


Original post by MathMan
Find the equation of the line AB and give express P (as it lies on AB) in terms the scalar parameter. Find the vector AP in terms of this scalar parameter and the vector BP and then I guess you can do it from there.


I was wondering how you know P is not between a and b?
Reply 7
it says P is on the line AB produced which places it beyond B
Reply 8
Original post by jack0213123
I was wondering how you know P is not between a and b?



Reply 9
Original post by steve2005


Thanks a lot mate for a clear answer
Reply 10
i have two questions , the first is magnitude ( a )=4 , magnitude ( b )=4 and magnitude( a -b)=7 find the ang le between vectors a and b

the second question is u= 5i-4j+sk , v= 2i+tj-3k
given that u and v are parallel find the values of the scalars s and t

help please

Quick Reply

Latest