Q&A for How to Multiply Matrices

This article should be helpful: how to find the inverse of a function .

You cannot multiply a 2x1 matrix with a 2x2 matrix together. To multiply two matrices together, the first matrix's columns and the second matrix's rows have to be the same. In this case, the first matrix only has 1 column, whereas the second one has two rows.

Use the dot product shown in the article above. (Note: You cannot switch the order and get the same answer, as matrix multiplication isn't commutative.)

They're used a lot in linear algebra and in solving systems of equations.