Welcome to the ACT math site for Ed-Co HS
Matrix (Matrices)- Is a rectangular array of real numbers
_ _
| a b |
|_c d _|
*To add Matrices, you just add the numbers that are in exactly the same spots.
___ ___ _ _
| -5 0 | + |6 -3 |
|_4__ 1 _| |_2 _3 |
Solution
- 1 -3
6 4
*When subtracting, you do the same thing as you do as adding.
A Matrix is an array of numbers:
A Matrix
(This one has 2 Rows and 3 Columns)
We talk about one matrix, or several matrices.
There are many things we can do with them ...
To add two matrices: add the numbers in the matching positions:
These are the calculations:
3+4=7
4+1=5
8+0=8
6-9=-3
The two matrices must be the same size, i.e. the rows must match in size, and the columns must match in size.
Example: a matrix with 3 rows and 5 columns can be added to another matrix of 3 rows and 5 columns.
But it could not be added to a matrix with 3 rows and 4 columns (the columns don't match in size)
The negative of a matrix is also simple:
These are the calculations:
-(2)=-2
-(7)=-7
-(-4)=+4
-(10)=-10
To subtract two matrices: subtract the numbers in the matching positions:
These are the calculations:
3-4=-1
4-1=3
8-0=8
6-(-9)=15
Note: subtracting is actually defined as the addition of a negative matrix: A + (-B)
We can multiply a matrix by some value:
These are the calculations:
2×4=8
2×1=2
2×0=0
2×-9=-18
We call the constant a scalar, so officially this is called "scalar multiplication".