Matrices are used in math, physics and computer science to represent an arrangement of numbers, equations or symbols. Often, matrices need to be manipulated, added, subtracted, multiplied or analyzed in some way. Because a matrix is simply a table of numbers, it is usually straightforward to enter numbers without resorting to special math software. However, you need to add large brackets on either side of your matrix to complete it.
Click the "Insert" tab on the ribbon, then click "Shapes" and select the left bracket from the "Basic Shapes" section to display a symbol that looks like a black cross.
Drag down and left to expand the symbol. Repeat the process to add the right bracket. Adjust the bracket as needed by clicking it and dragging one of the handles. You can also nudge the brackets by using the arrow keys on your keyboard.
Click the "Format" tab, then select a different color or line weight for your brackets.