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Algebra 2

Today:• Class Announcements• PLAN Practice• 4.1 Notes• Begin Homework• Show Chapter 3 Test Scores

Vocabulary:entry, scalar multiplications

4.1 – Matrix Operations

Objectives:• Identify the characteristics of a

matrix• Add and subtract matrices• Multiply scalars • Solve a matrix equation

Anatomy of a Matrix (Matrices)

Identifying the dimensions of a matrix: # of Rows x # of Columns

a b c d

e f g hRows

Columns

A is a 2x3 matrix

210

246A

Identify this matrix:

02

53BB is a 2x2 matrix

Anatomy of a Matrix (Matrices)

Identify this matrix:

119422

30411

11023

CC is a 3x5 matrix

A is a 2x3 matrix

210

246A

Anatomy of a Matrix (Matrices)

Identify this matrix:

210

412

312

132

DD is a 4x3 matrix

A is a 2x3 matrix

210

246A

Anatomy of a Matrix (Matrices)

Identify this matrix:

7

2

3

Ecolumn matrix

A is a 2x3 matrix

210

246A

Anatomy of a Matrix (Matrices)

Identify this matrix:

0232F row matrix

A is a 2x3 matrix

210

246A

Anatomy of a Matrix (Matrices)

Identify this matrix:

321

310

543

Gsquare matrix

A is a 2x3 matrix

210

246A

Anatomy of a Matrix (Matrices)

Identify this matrix:

00

00

00

Hzero matrix

A is a 2x3 matrix

210

246A

Anatomy of a Matrix (Matrices)

c1b

24aJ

210

246A

Matrices are equal if they are the same size and each entry is equal.

Anatomy of a Matrix (Matrices)

210

246A

c1b

24aJ

6 4 -2 a 4 -2=0 1 2 b 1 c

a = 6b = 0c = 2

Anatomy of a Matrix (Matrices)

Find a, b, and c if A = J.

3-y1x

242zK

210

246A

Matrices are equal if they are the same size and each entry is equal.

Anatomy of a Matrix (Matrices)

210

246A

3-y1x

242zK

2z 4 -26 4 -2=x 1 y-30 1 2

x = 0y = 5z = 3

Find x, y, and z if A = K.

Anatomy of a Matrix (Matrices)

Adding and Subtracting MatricesTo add or subtract matrices:

1. Matrices same size2. Add/subtract same entries

3-810

226-M

12

43N

51

00

23

P

10

52Q

523

024R

Find:L + M

6 4 -2L=0 1 2

0 6 -4

10 9 -1

Find:M + NNot possible; sizes not equal

To add or subtract matrices:1. Matrices same size2. Add/subtract same entries

3-810

226-M

12

43N

51

00

23

P

10

52Q

523

024R

Adding and Subtracting Matrices

6 4 -2L=0 1 2

Find:N + RNot possible; sizes not equal

To add or subtract matrices:1. Matrices same size2. Add/subtract same entries

3-810

226-M

12

43N

51

00

23

P

10

52Q

523

024R

Adding and Subtracting Matrices

6 4 -2L=0 1 2

Find:M – R

-2 0 -2

13 10 -8

To add or subtract matrices:1. Matrices same size2. Add/subtract same entries

3-810

226-M

12

43N

51

00

23

P

10

52Q

523

024R

Adding and Subtracting Matrices

6 4 -2L=0 1 2

Find:P – LNot possible; sizes not equal

Add and Subtracting MatricesTo add or subtract matrices:1. Matrices same size2. Add/subtract same entries

3-810

226-M

12

43N

51

00

23

P

10

52Q

523

024R

6 4 -2L=0 1 2

Find:Q – N

1 1

2 0

Add and Subtracting MatricesTo add or subtract matrices:1. Matrices same size2. Add/subtract same entries

3-810

226-M

12

43N

51

00

23

P

10

52Q

523

024R

6 4 -2L=0 1 2

Multiply ScalarsTo multiply a scalar:1. Multiply the scalar with every

entry

Perform the scalar multiplication:

210

2466

21

343-

36 24 -12

0 6 12

-12 -9

3 -6

Solving a Matrix EquationTo solve a matrix equation:1. Simplify both sides of the

equation.2. Set up equations and solve3. Present answers4. Check

Solve:

80

48-48

61

2x-4

2y1-

084

x = 6, y = -2

To solve a matrix equation:1. Simplify both sides of the

equation.2. Set up equations and solve3. Present answers4. Check

Solve:

2118

9-0

11-

5x

4y5

2103

x = 10, y = 2

Solving a Matrix Equation

Assignment:pgs. 203-204 #15-17, 29, 30, 34,

35

4.1-4.3 Quiz on Tuesday, October 30th

Algebra 2

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