1. 13.1 Matrices and Their Sums

2. A is a rectangular arrangement of numbers in rows and columns.
Matrix A below has two rows and three columns. The of matrix A are 2X3 (two by three; rows then columns). The numbers in the matrix are called
matrix
dimensions
elements
2 rows
3 columns

3. Types of Matrices Name Description Example Row Matrix has only one row
Column Matrix
Square Matrix
has only one row
has only one column
has same number of
rows as number of
columns (i.e. 2X2)

4. For two matrices of the same dimensions, the entries in the same row and same column are said to be entries.
Two matrices are if and only if they have the same dimensions and all of their corresponding entries are equal.
corresponding
equal

5. Find the value of the variables for which the given statement is true.1.

6. Find the value of the variables for which the given statement is true.2.

7. If two matrices A and B have the
If two matrices A and B have the dimensions, then their sum, A + B, is the matrix of the same dimensions whose entries are the sums of the entries of A and B.
same
corresponding

8. Find the sum. 3.

9. Find the sum. 4.

10. Zero Matrix
Zero Matrix: Also called the identity matrix for addition

11. Opposite Matrix Note: , so –A is the additive of A.
Opposite Matrix: Changes the sign of each element in the matrix
Note: , so –A is the additive of A.
When subtracting two matrices, we the of the subtracted matrix.
inverse
add
opposite

12. Find the difference. 5.

13. Find the difference. 6.

14. Find the value of the variables for which the given statement is true.7.