How to use algebra tiles to factor quadratic trinomials - 4 examples with pictures

Algebra tiles are great for making math visual and allowing math students to better connect with more complicated algebra topics. This post has 4 examples with lots of pictures for how to use algebra tiles to factor quadratic trinomials. Includes a link to a free printable set of algebra tiles in pdf format. Algebra tiles make factoring visual and can be used to make factoring quadratic trinomials visual, hands-on and intuitive.

Algebra tiles are the coolest little things. They are a wonderful hands-on tool that can be used to visually represent so many topics in algebra, from solving equations to multiplying binomials to factoring quadratic trinomials.

This post has 4 examples with lots of pictures for how to use algebra tiles to factor quadratic trinomials. Includes a link to a free printable set of algebra tiles in pdf format. Algebra tiles make factoring visual and can be used to make factoring quadratic trinomials visual, hands-on and intuitive.

In this post, I want to focus on that last topic -- using algebra tiles to factor quadratic trinomials. Algebra tiles are a perfect way to introduce and practice this concept. They take a lot of the guesswork out of factoring, especially for trinomials that are not easily factored with other methods. 

Below are 4 examples of how to use algebra tiles to factor, starting with a trinomial where A=1 (and the B and C values are both positive), all the way to a trinomial with A>1 (and negative B and/or C values).  

Here is a look at the tiles in this post:

Using algebra tiles to make factoring quadratics visual

In my set of algebra tiles, the same-size tiles are double-sided with + on one side and - on the other. You can get a similar effect by printing this free printable set of algebra tiles on astrobrights paper (or glue 2 different colored pieces of paper together back-to-back before cutting). 

Let's jump into the examples!


Example 1: 

Factor x2 + 5x + 6


Factoring this trinomial is a nice place to start because the A value is 1 and both the B and C values are positive. We'll be able to get a good feel for how the algebra tiles work with this example.

Needed:
1 x2 tile 
5 rectangular x tiles
6 + tiles

example #1 - using algebra tiles to factor a quadratic trinomial with A=1 and no negatives

Here we have all of the tiles we will need to factor this trinomial. Now it's just a matter of putting the puzzle together.

example #1 - using algebra tiles to factor a quadratic trinomial with A=1 and no negatives

First, I tried (x + 4)(x + 1). This used all of the rectangular x tiles but not all of the + tiles. In order for the trinomial to be factored correctly, all tiles have to fit together to make a perfect rectangle.

example #1 - using algebra tiles to factor a quadratic trinomial with A=1 and no negatives

Next I tried (x + 2)(x + 3), which allowed all 6 of the + tiles to fit. 

x2 + 5x + 6 factors to (x + 2)(x + 3).


Example 2

Factor 2x2 + 3x + 1


Algebra tiles are great for factoring quadratic trinomials where the A value is not 1. I have always liked the AC method for factoring these trinomials, but even I will admit that factoring with algebra tiles in this instance is all around way better.

Needed:
2 x2 tiles
3 rectangular x tiles
1 + tile

How to factor a trinomial with algebra tiles when the A value is greater than 1

Here we have all the tiles we need to factor this trinomial. With trinomials where the A, B and C values are all positive, we start and finish with the same number of tiles. (In a minute when we factor a trinomial where B and/or C are negative, the approach will be slightly different.)

How to factor a trinomial with algebra tiles when the A value is greater than 1

Arranging the algebra tiles into (x + 1)(2x + 1) allowed all of the tiles to fit together into a nice, neat rectangle.

2x2 + 3x + 1 factors to (x + 1)(2x + 1).


Example 3

Factor x2 - x - 12


How to use algebra tiles to factor a quadratic trinomial with negatives

When we factor quadratic trinomials involving negatives, we may not start and end with the same number of tiles. We may have to add in some zero pairs as we go. In the case of x2 - x - 12, our B value is -1.

Needed (to start):
1 x2 tile
1 rectangular -x tile
12 - tiles

How to use algebra tiles to factor a quadratic trinomial with negatives

Since there was no way to make a rectangle that fit those 12 - tiles, we needed to add in some additional zero pairs (1 of each rectangular + and - x tile).

We can do this because:

-1 + 0 = -1 or
-2 + 1 = -1 or
-3 + 2 = -1 .... and so on...

By adding in equal amounts of rectangular + and - x tiles, we are not changing the trinomial's B value. It's still -1.

How to use algebra tiles to factor a quadratic trinomial with negatives

Here we have 3 rectangular -x tiles and 2 rectangular x tiles. Still not enough to fit those 12 - tiles, though the B value is still being represented as -1.

Using algebr tiles to factor a trinomial with negatives

We got it! We needed 4 rectangular -x tiles and 3 rectangular x tiles to make all 12 - tiles fit. -4 + 3 - =1 so we did not change the trinomial's B value.

x2 - x - 12 factors to (x - 4)(x + 3).


Example 4

Factor 2x2 + x - 3


Using Algebra tiles to factor a trinomial with A>1 and negatives

Using Algebra tiles is so helpful when factoring quadratic trinomials where the A value is greater than 1 and B and/or C are negative. The tiles make the process so much more intuitive!

Needed (to start):
2 x2 tiles
1 rectangular x tile
3 - tiles

Using Algebra tiles to factor a trinomial with A>1 and negatives

Right away it's obvious that we do not have enough pieces to make a nice, even rectangle. So we will need to start adding zero pairs to keep B at +1. Here I added a rectangular +x and a rectangular -x. This wasn't quite enough to fill it in.

Using Algebra tiles to factor a trinomial with A>1 and negatives
I added one more zero pair of x tiles and our rectangle is complete!

2x2 + x - 3 factors to (x - 1)(2x + 3).


I had gotten this set of algebra tiles secondhand online. If you don't have a set, you can print this free set of printable algebra tiles.

free printable set of algebra tiles

There are 2 versions of the algebra tiles in the pdf. The first page mirrors the dimensions of my plastic set. The algebra tiles on the second page are a little larger for kids who may have trouble with the smaller size.

There are also a bunch of online algebra tile sites. This one gives example problems to factor and has tiles to drag into a workspace.

Voyage to the Treasure factoring quadratic trinomials game

I've been working with a friend on a new math game series called Voyage to the Treasure where students work together to beat the game board. This factoring trinomials game covers trinomials where A=1. There are more Voyage to the Treasure games, a video and a more detailed set of directions in this post.

algebra tile references - Algebra word wall

I added these algebra tile references into my algebra word wall so that students can make the connection between factoring and area. The vertex form model is cool because a quadratic in vertex form is missing a few pieces because of that k value at the end. 


Related posts:

Solving Equations Using Algebra Tiles

Cereal Factoring

Fun with Quadratics

Scaffolded Math and Science blog

Are you looking to use algebra tiles to make factoring more visual? In this post are 4 examples of how to use algebra tiles to factor quadratic trinomials, including trinomials where A>1 and with negative B and C values. Also includes a link to a free printable pdf set of algebra tiles to use in your math classroom.


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