1. Day 27 Agenda:
DG minutes
Scientific Calc only

2. Lesson 3: Determinants Matrices
Accel Precalculus
Unit #3: Matrices
Lesson 3: Determinants Matrices
EQ: How do you calculate the determinant of a 2 x 2 and a 3 x 3 matrix?

3. Definition of Determinant of a 2 x 2 Matrix
Given
I. notation for the determinant
(notice – no hooks at the top or bottom!)
II. formula for the determinant

4. Definition of Determinant of a 2 x 2 Matrix

5. det(S)= det(T)= (-3)(9) – (-2)(4) (-6)(4) – (-2)(12) -27 + 8 -24 + 24
Ex. 1 Find the determinant for each matrix.
det(S)= det(T)=
(-3)(9) – (-2)(4)
(-6)(4) – (-2)(12)
-19

6. Ex. 2 Find the determinant for these matrices.
b) det(B) = -3
a) det(A) = 7

7. Finding the Determinant of a 3 x 3 Matrix:

8. Ex. 3 Find the determinant of the given matrix.
= 1(11 – 48)
= 1(11 – 48) – 0( ) – 4( )
= 1(11 – 48) – 0( )

9. Ex. 4 Find the determinant of the given matrix.
= 3(3•8 - 8•0) – 1(6•8 - 0•6) + 8(6•8 - 3•6) = 264

10. Ex. 5 Find the determinant of the given matrix.
-2(-5)

11. = -3(2•1 – 0•1) + -1(0•1-4•1) – 2(0•0 - 4•2) = 14
***You can choose any row to begin, just alternate the signs.
= -3(2•1 – 0•1) + -1(0•1-4•1) – 2(0•0 - 4•2) = 14

12. 1. det(A) = 2 2. det(B) = 10 3. det(C) = 0 1. 2. 3.
In Class Practice: Find the determinant of each matrix. 1.
1. det(A) = 2 2.
2. det(B) = 10
3. det(C) = 0 3.

13. ASSIGNMENT:
Textbook p.596 #2 - 12