Factoring Trinomials: Positive Negative Signs

Lesson Procedure:

Print the classroom lesson plan and worksheet questions (see below).

Lesson Excerpt:

Factoring Trinomials with different signs

- “The trinomials that we have been factoring have had all positive signs in them, so when we factored them we could just add in the positive signs. Now we are going to start factoring trinomials that have different signs. Here is an example.”

- On Board: x2 – 4x + 4
- “Now in working with this trinomial, we are going to start out the same way. We can easily factor the x2 into two binomials, so that is where we are going to start.”
- On Board: (x )(x )
- “The next step remains the same too, but it is going to take a little more thinking to figure out the factors that work. We are looking for two factors that add together to equal the second term, but multiply together to equal the third term.”

Continued...