1. Do Now: Solve each equation:

2. Workbook page 21
yes; 7 x ) yes; 2 x ) yes; 1 x 1 9)
11) )

3. Workbook page 21
19)
20) ) $526,054

4. Determinants

5. **To find a determinant you must have a SQUARE MATRIX!!**
Determinant - a square array of numbers or variables enclosed between parallel vertical bars.
**To find a determinant you must have a SQUARE MATRIX!!**
Finding a 2 x 2 determinant:

6. Find the determinant:

7. Expansion by Minors
Always:

8. Finding a 3x3 determinant: Expansion by Minors Method
6. Evaluate
Step 1: Expand the matrix into 3 pieces.
Step 2: Evaluate each 2x2 matrix.
Step 3: Simplify. 21

9. Finding a 3x3 determinant: Diagonal method
Step 1: Rewrite first two columns of the matrix.

10. 126 - (-52) 126 + 52 = 178 Step 2: multiply diagonals going up!
-224
+10
+162
= -52
Step 2: multiply diagonals going up!
Step 2: multiply diagonals going down!
+12
-126
+240
=126
Step 3: Bottom minus top!
126 - (-52)
= 178

11. 38 - 38 = 0 Step 2: multiply diagonals going up!
-18
+50 +6
= 38
Step 2: multiply diagonals going up!
Step 2: multiply diagonals going down!
- 15 45
+ 8
= 38
Step 3: Bottom minus top!
= 0

12. Do Now: Copy down this problem.
Find the area of a triangle whose vertices are located at (-1, 6), (2, 4), (0, 0).