Video:How to Add Matrices

Transcript:How to Add Matrices

Hi, my name is Bassem Saad. I'm a Math Ph.D. candidate at U.C. Davis, and I'm here today for About.com to show you how to add matrices.

Adding A Matrix's Rows and Columns

Remember, a matrix is a rectangular array with m rows and n columns; and for us, these rows and columns will be full of numerical entries. For example, this is a two-by-three matrix, with two rows and three columns, and all the entries are integers. Remember, when you add two matrices, you're only really adding their corresponding entries; and you can only add two matrices if they're the same size.

Let's add these two matrices: minus two, plus one, is minus one; zero, plus two, is two; one, plus minus one, is zero; four, plus zero, is four; three, plus three, is six; and five, plus minus two, is three.

Two-by-Two Matrix Addition

Let's take a look at another example. This time we're adding two, two-by-two matrices; that is, two rows and two columns. And, again, we have to make sure they're the same dimension – and, of course, they are. So, we get the first entry here, by adding the first entry with the first entry here. So one plus zero, is just one. Then this entry is one, plus one, which is two. This entry is zero, plus pi, which is just pi. And, finally, the last entry is minus one, plus one, which is just zero.

In every day life, professionals that deal with large collections of data must be able to add matrices. This includes video game programmers, financial experts, and scientists. And your computer is adding matrices in the background all the time. Thanks for watching, and to learn more, visit us on the web at About.com.