# Proving that vector addition is associative

• Mar 8th 2011, 08:15 PM
brumby_3
Proving that vector addition is associative
Complete the following non diagram proof that vector addition is associative:

For all points P, Q, R, S, (PQ + QR) + RS = PR + ...........
...........
...........
= PQ + (QR + RS)

Note that all the letters ie 'PQ' etc have an arrow above them --->, not a single one for all, but one above each letter pair.
• Mar 9th 2011, 02:28 AM
HallsofIvy
• Mar 9th 2011, 01:38 PM
poirot
Quote:

Originally Posted by brumby_3
Complete the following non diagram proof that vector addition is associative:

For all points P, Q, R, S, (PQ + QR) + RS = PR + ...........
...........
...........
= PQ + (QR + RS)

Note that all the letters ie 'PQ' etc have an arrow above them --->, not a single one for all, but one above each letter pair.

You are simply adding the individual components (x,y,z etc) so its simply a case that addition is associative.
• Mar 9th 2011, 01:57 PM
brumby_3
Nevermind, I understand now, thanks :)