1. Section 3.3 – The Inverse of a Matrix
No Calculator

2. The 2 x 2 Inverse
Find the inverse of OR
1. Find det A
a. If det A = 0, no inverse
b. If , continue to 2.
Switch elements of main diagonal
(blue elements)
Change signs of off diagonal
(red elements)

3. Find the inverse of
Find the inverse of

4. Find the inverse of each of the following matrices:
NO INVERSE
12 – 12 = 0

5. The 3 x 3 Inverse
1. Find the determinant of the matrix (given)
a. If det A = 0, no inverse.
b. If , continue to 2.
2. Find the values of the NINE minors.
3. Place +/- into the resulting matrix. (diamond)
4. “Transpose” the matrix (switch rows and columns)
5. Write final answer.

6. Step 1
Find the inverse of A if
Step 2

7. Step 2 Answer:
Step 3
Step 4
Step 5

8. Find the inverse of A if
Complete Step 2 only. You need not show work.

9. Step 2 Answer
Complete Steps 3, 4 and 5.
Step 3
Step 4
Step 5

10. Find the inverse of A if
Complete Step 2 only. You need not show work.

11. Step 2 Answer
Complete Steps 3, 4 and 5.
Step 3
Step 4
Step 5

12. Find the inverse of each of the following matrices: