1. The Identity and Inverse Matrices
Get out your notes and purple sheet and get ready for a warm-up!

2. Warm-Up
Determine if there is an inverse for the following matrix. If there is, find the inverse.

3. Reminders… 1 0 0 1 1 0 0 0 1 0 0 0 1 𝑎 𝑏 𝑐 𝑑 −1 = 1 𝑎𝑑−𝑏𝑐 𝑑 −𝑏 −𝑐 𝑎
What is the identity for a 2x2? 3x3?
How do we know if a matrix has an inverse?
Find the determinant. If the determinant doesn’t equal 0, then it exists.
What is the formula for the inverse once we know it exists?
𝑎 𝑏 𝑐 𝑑 −1 = 1 𝑎𝑑−𝑏𝑐 𝑑 −𝑏 −𝑐 𝑎

4. Closure
Find the inverse.