**In class**we covered the definition and method for deriving identity and inverse matrices. We learned to solve systems of equations like

Using matrices

We would then solve the system. Multiplying on the inverse on both sides

We get

So, since is the 2-by-2 identity matrix, we have

We also looked at solving systems of inequalities

**Assignment:**

6.4 on p. 331: 3, 6-10, 15, 17, 18

6.5 on p. 339: 5-9, 11-15