1. Introduction To Matrices
Chapter 4.1
Introduction To
Matrices

2. Def: A matrix is a rectangular array of elements in rows and columns
Notation: [ ]
For example
Row
Column
Def: Each number in a matrix is called
an element.

3. Notation: A matrix with 8 rows and 5 columns
is a 8 x 5 matrix C8x5
1. Find the element in row 6 column 4

4. 2. How many rows and columns does matrix R have? R3x2
3. What are the dimensions of matrix A?
A =

5. “The element in matrix A in the 2nd row and 3rd column”
4.) Find: A23
“The element in matrix A in the 2nd row
and 3rd column”
In a matrix, information is
designated by its address
A =
Read as:

6. 5. You can multiply a matrix by a number (scalar multiplication)
Def: Two matrices are equal if they have the same dimensions and if each element of one matrix is equal to the corresponding element of the other.

7. 6. Are these matrices equal?
and
Not equal
Same elements
but not the same
dimensions
2x3
3x2
7. Are these matrices equal?
Equal
Elements are
equal and the
same
dimensions
and
2x2
2x2

8. Solve by setting them equal
You can use the fact that corresponding elements are equal to solve a matrix equation 8.
Solve by setting them equal
Both 2x1 matrices

9. 9. solve
Both 2x1 matrices

10. 10.) A triangle has the following vertices:
Vertex
(A) (B) (C)
A (2, 3)
B (-3, -3)
C (1, -4) x
• 2 = y
Enlarge ABC
so its perimeter
Is twice the original
length

11. 10.) (cont.)
•2 =

12. Homework
Page 191
Problems: 13-24, and 28