# Do all matrix multiplication methods boil down to dot product?

Following the video from MIT's OCW, the Prof. brings up many different methods, like $$row * matrix$$, $$column * matrix$$, etc. Yet don't these all come down to dot product. For example $$row * matrix$$ would be done using dot product, right? Is the Prof just showing all of these things to show the big picture, or what?

A little bonus: The Prof says that with the multiplication of the matrices A and B (AB) equaling to C, that the rows of C are a combination of the rows of A. Here, the columns of B must be multiplied by the matrix A (column * matrix method) to get one column of C. So, to do this you would end up doing the columns of B times all the rows of A (using dot product, right, question above), yet he says that the columns of C are a combination of the columns of A, is this just because when doing all of the rows, the columns will technically be included?

Thanks for all the help!

• The definition of matrix multiplication comes down to dot product Jul 11 '19 at 15:35
• Alright, thanks, so just to clarify everything else is showing different ways you can use it? Also, could you maybe look at the bonus? Thanks for the extremely quick help! Jul 11 '19 at 15:39
• Yes, Dr. Strang is just showing different ways of thinking about it. Jul 11 '19 at 15:50
• @saulspatz Alright, thanks a million, you just cleared so much up! Jul 11 '19 at 15:54
• @saulspatz Prof. Strang is the best, isn't he! Jul 11 '19 at 15:54