4.1 Using Matrices to Represent Data
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Transcript 4.1 Using Matrices to Represent Data
4.1 Using Matrices to
Represent Data
Objectives: Represent mathematical and realworld data in a matrix. Find sums and
differences of matrices and the scalar product of
a number and a matrix
Standard: 2.8.11.I. Use matrices to organize and
manipulate data, including matrix addition,
subtraction, multiplication, and scalar
multiplication.
The table below shows business activity for one
month in a home-improvement store. The table shows
stock (inventory on June 1st), sales (during June), and
receipt of new goods (deliveries in June).
Sales
(June)
Inventory
(June 1st)
Deliveries
(June)
Small
Large
Small
Large
Small
Large
Picnic
Table
8
10
7
9
15
20
BQ
grills
15
12
15
12
18
24
You can represent the inventory
data in a MATRIX.
Small
Large
Picnic
Table
8
10
BQ
grills
15
12
* A _______________ (plural _____________) is a rectangular array of
numbers enclosed in a single set of
brackets.
* The _____________ of a matrix are the
number of horizontal rows and the number
of vertical rows it has. If a matrix has 2 rows
and 3 columns, its dimensions are
__________, read as “ __
.” The
inventory matrix above, M, is a matrix with
dimensions of _______________.
* Each number in the matrix is called an
______________, or element.
Ex 1. Represent the June sales data in matrix
S. Interpret the entry at S12.
Ex 2. Represent the June delivery data in
matrix D. Interpret the entry at D21.
* 2 matrices are equal if they’ve the same
_____________ & if corresponding entries are
___________________.
* Ex. 2 Solve for x and y.
4x + 5
9
15
21
9
15
=
7
-2y + 3
-1
7
y – 12
-1
To find the sum (or difference) of matrices A and B with the
same dimensions, find the sums (or differences) of
corresponding entries in A and B.
* Ex. 2 Let
and
* To multiply a matrix, A, by a real number, k, write
a matrix whose entries are k times each of the
entries in matrix A. This operation is called
_____________________________
* Let
Find -3A.
* When k = -1, the scalar product kA is -1A, or
simply –A, and is called the _____________
or opposite, of matrix A. For example,
* Let
then –A = ___?____
is the additive inverse
of A.
Writing Activities
1). If A represents a matrix, explain what
-5A represents.
2). If M is 4 X 5 matrix, explain what the
numbers 4 and 5 represent.