Last modified on 16 December 2010, at 23:12

GCSE Mathematics/Matrices

Adding/subtracting matricesEdit

When adding or subtracting matrices you should add/subtract numbers in the same position, like this:

\begin{bmatrix}
1 & 5 \\
4 & 2 \\
\end{bmatrix} + \begin{bmatrix}
7 & 2 \\
5 & 3 \\
\end{bmatrix} = \begin{bmatrix}
8 & 7 \\
9 & 5 \\
\end{bmatrix}
\begin{bmatrix}
7 & 5 \\
4 & -2 \\
\end{bmatrix} - \begin{bmatrix}
-1 & 2 \\
-3 & 5 \\
\end{bmatrix} = \begin{bmatrix}
8 & 3 \\
7 & -7 \\
\end{bmatrix}

Matrices can only be added/subtracted if they are of the same size.

Multiplying matricesEdit

When multiplying matrices by a number, you should multiply all the numbers inside them by that number, for example:

2\begin{bmatrix}
1 & 3 \\
4 & 2 \\
\end{bmatrix} = \begin{bmatrix}
2 & 6 \\
8 & 4 \\
\end{bmatrix}