SOLUTION: Hi again, just wanted t know if the question I have been asking has something wrong with it, because I havnt received any kind of response to it at all. If not can someone please h

Algebra ->  Matrices-and-determiminant -> SOLUTION: Hi again, just wanted t know if the question I have been asking has something wrong with it, because I havnt received any kind of response to it at all. If not can someone please h      Log On


   

Question 222736: Hi again, just wanted t know if the question I have been asking has something wrong with it, because I havnt received any kind of response to it at all. If not can someone please help me. The following questions are for two seperate hypothetical matrices.
Here they are again:
Suppose MATRIX AB is defined.
a) If A is 4*6 and B is a column matrix, give the dimensions of B and AB.
b) (different matrix) If A is the identity matrix and B is 6*6, what size is A?
Thanks, -Nick.
Answer by user_dude2008(1862) About Me  (Show Source):
You can put this solution on YOUR website!
a) If A is 4 x 6, then B is 6 x 1 (inner dimensions must match)
So AB is 4 x 1

b) "A is the identity matrix " --> A is square (num rows = num columns)

Since AB is defined, A is 6 x 6 also since inner dimensions must match