Question

In R4 you are given the points

P(2,2,2,2), Q(9,−5,1,3), R(6,8,−4,1)
(a) Write out all possible arrows which can be formed using the points P,Q,R.

Answer 1

it's the same as the number of ways to permute 2 of 3 things: 3P2 = 6