1. Lesson 13-2: Adding & Subtracting Matrices
Objectives:
Students will:
Add & subtract matrices
Find the additive inverse of a matrix

2. ► Use a capital letter to name a matrix
Adding & Subtracting:
► Use a capital letter to name a matrix
► Matrices must have same dimensions (to add or subtract)
► Add (subtract) by adding (subtracting) corresponding elements
Example 1: Find A + B

3. Example 3: Find the additive inverse of A =
Matrix with the opposite elements of a given matrix
If given a matrix A additive inverse is denoted –A
Can add the additive inverse instead of subtracting
(like integers) A –B = A + -B
Example 3: Find the additive inverse of A =
-A =

4. Try it 2: Find A – B

5. Lesson 13-3: Determinants & Cramer’s Rule
Objective:
Students will:
Evaluate determinants and
Solve systems using Cramer’s Rule

6. All square (2 x 2, 3 x 3,…) matrices have a determinant
2 x 2 determinant:
Difference of products from diagonals (main diagonal 1st)
Notation | |
Example 1
Solution:-8

8. Cramer’s Rule (cont’d) then…
so…
and
if needed

9. Example 2 Solve Using Cramer’s Rule
4x + 3y = 1
2x + y = 5 D=
Dx=
Dy=
Solution is (7, -9)

10. Assignment
13-2/575/ 1-19o
13-3/ / 1-13 o, 27-32