Question

Can someone explain how the following Matrix can be multiplied? I thought the column of the first matrix had to match the row of the second and the row of the first had to match the column of the second. I how the matrices listed below as (1x3) and (3x3) respectively. Yet my online Pre-cal course says it's possible. Please explain why this is so.

Answer 1

You are correct in thinking that the columns of the first matrix must match with the rows of the second matrix.

So for example, we can multiply a 1 x 5 matrix with a 5 x 7 matrix. The two matching '5's are directly what make multiplication possible in this case. For your problem, the first two '3's match and multiplication is possible.

The rows of the first matrix don't need to match with the columns of the second matrix.