You know how some buildings have a 13th floor, but the elevator never goes there and no one ever talks about it? Well, Section 3.9 is the equivalent to such a superstitious level. You won't find it in your book, and no other teacher or student will talk about it. It's extremely TOP SECRET.

Algebra II 3 (A) formulate systems of equations, including systems consisting of three linear equations in three variables and systems consisting of two equations, the first linear and the second quadratic

Algebra II 3 (B) solve systems of three linear equations in three variables by using Gaussian elimination, technology with matrices, and substitution