Linear Combinations: 7:08
At 10:20 I meant to say 1/2!!!
This video makes it seem like you can only do linear combinations of two vectors each in R^2. The truth is, you can have any number of vectors in a linear combination and they can be in any dimensional space.
Keep in mind, however, that you can't add a vector with, say, 3 entries to a vector with 5 entries. Therefore, vectors in a given linear combination must have the same number of entries.