1. Identity and Inverse Matrices

2. Key Topics Identity matrix: a square matrix, multiplied with another matrix doesn’t change the other matrix (just like 1 is the multiplicative identity of real numbers)

3. Identity Matrix in Action Notice: These two matrices are the same. Multiplying by the identity matrix changed nothing

4. Key Topics You might be wondering: why do I tell you about the identity matrix ?? If it doesn’t do anything, why do we need to know what it is ?? Inverses: two nXn matrices are inverses of each other if their product is the identity matrix

5. Checking for Inverse Matrices Determine whether the following pairs of matrices are inverses of one another:

6. Finding 2X2 Inverse Matrices To find the inverse of a 2X2 matrix, use the following method: Basically this tells us to calculate the determinant, then multiply it’s inverse by the rearranged matrix having a and d switch places and b and c as the opposite values Inverse of Determinant Rearranged matrix A -1 is the notation used to represent the inverse of matrix A If determinant is 0 there is no inverse!!

7. Practice Find the inverse matrix for the following matrices: N/A