ATAR Notes: Forum

Uni Stuff => Science => Faculties => Mathematics => Topic started by: bturville on March 30, 2008, 02:39:15 pm

Title: Quick vector question
Post by: bturville on March 30, 2008, 02:39:15 pm: Let k=3i - 5j + 2k and v= 2i + 2j.

Is it possible to find 2k - 4v? Can you do it, with them both being in different dimensions (ie R^2 and R^3)?
Title: Re: Quick vector question
Post by: Collin Li on March 30, 2008, 03:26:50 pm: No, you cannot. It is like adding a 3x1 matrix with a 2x1 matrix.
Title: Re: Quick vector question
Post by: Mao on March 30, 2008, 04:51:32 pm: can you not assume v is on the i-j plane, and therefore v=2i+2j+0k??
Title: Re: Quick vector question
Post by: Collin Li on March 30, 2008, 05:21:00 pm: Vectors are analogous to matrices. It is not like real numbers and their relationship to complex numbers, where there is an implied $0i$ . You just can't add them. If you wanted to add them for some practical application, the 2-dimensional vector would have been better off defined in an i-j plane of an i-j-k world (i.e.: with a k component equal to zero). Technically, looking at this with a mathematical viewpoint only, you can't do it.