Factor any trinomial ax² + bx + c using the Tic Tac Toe (Box) Method — step-by-step
| Step | Action | Example (2x²+7x+3) | Result |
|---|---|---|---|
| 1 | Identify a, b, c | a=2, b=7, c=3 | Coefficients known |
| 2 | Find GCF of a, b, c | GCF(2,7,3) = 1 | No common factor |
| 3 | Compute product a×c | 2 × 3 = 6 | Target product = 6 |
| 4 | Find factor pair of ac that sums to b | 1×6=6, 1+6=7 ✓ | Pair: 1 and 6 |
| 5 | Fill the 2×2 box | ax² | 6x / 1x | c | Box filled |
| 6 | Find GCF of each row & column | Row 1: 2x, Row 2: 1; Col 1: x, Col 2: 3 | Edge factors found |
| 7 | Write the two binomials | (2x+1)(x+3) | Factored form |
| 8 | Verify with FOIL | 2x²+6x+x+3 = 2x²+7x+3 ✓ | Confirmed correct |
| Trinomial Type | Condition | Example | Factored Form |
|---|---|---|---|
| Simple (a=1, pos) | b>0, c>0 | x²+5x+6 | (x+2)(x+3) |
| Simple (a=1, mixed) | b<0, c>0 | x²−5x+6 | (x−2)(x−3) |
| Simple (a=1, neg c) | c<0 | x²+x−6 | (x+3)(x−2) |
| Leading coefficient | a>1 | 2x²+7x+3 | (2x+1)(x+3) |
| Perfect Square Trinomial | b²=4ac | x²+6x+9 | (x+3)² |
| Difference of Squares | b=0, c<0 | x²−9 | (x+3)(x−3) |
| Not factorable (prime) | No integer pair | x²+x+1 | Prime (use formula) |
| Negative leading coeff. | a<0 | −x²+5x−6 | −1(x−2)(x−3) |
| Target Product | Factor Pairs (positive) | Possible Sums | Possible Differences |
|---|---|---|---|
| 6 | 1×6, 2×3 | 7, 5 | 5, 1 |
| 8 | 1×8, 2×4 | 9, 6 | 7, 2 |
| 10 | 1×10, 2×5 | 11, 7 | 9, 3 |
| 12 | 1×12, 2×6, 3×4 | 13, 8, 7 | 11, 4, 1 |
| 15 | 1×15, 3×5 | 16, 8 | 14, 2 |
| 18 | 1×18, 2×9, 3×6 | 19, 11, 9 | 17, 7, 3 |
| 20 | 1×20, 2×10, 4×5 | 21, 12, 9 | 19, 8, 1 |
| 24 | 1×24, 2×12, 3×8, 4×6 | 25, 14, 11, 10 | 23, 10, 5, 2 |
| 30 | 1×30, 2×15, 3×10, 5×6 | 31, 17, 13, 11 | 29, 13, 7, 1 |
Tic Tac Toe factoring is a way to solve square expressions. It uses the grid of Tic Tac Toe to sort the task and simplify the process. The main idea is to place the coefficients of the square expression in separate cells of the Tic Tac Toe board.
Later the grid helps group the parts of the expression like this, so one finds two binomial factors.
The method works by filling the grid with pairs of numbers, that multiply to form the parts of the expression. That is a visual and sorted way, that aims to factor square trinomials. The whole process requires nine steps to set up and finish the Tic Tac Toe board.
When one finishes all steps, the factored form of the trinomial appears directly on the board. One can porcess a sample step by step, to show how the whole method works.
The coefficients a, b and c of the square expression go each in their own place on the board. That stage is very simple. The hard part is finding what numbers belong in the other cells.
But that is exactly what the grid aims to help with. It makes sure that everything stays sorted, so nothing gets missed during the process.
Tic Tac Toe factoring links also to several other math topics. It deals with simplifying radicals, common denominators, solving logarithms with a calculator and going from word form too normal form. That fits lessons about mid-level algebra and high school algebra with review.
Even programs for factoring in calculators like the Casio use similar ideas.
That method does not limit to just practice. One can turn it into a game for the whole group. It works well in math stations, small groups of teaching or teamlearning labs.
Students play Tic Tac Toe in pairs, while they factor square equations. The expressions carry both positive and negative integers, so there is good variety of tasks. Some versions have five boards, that become more challenging, when students progress through them.
Usually one includes an answer key, so checking the work is easy.
Another way to practice factoring of polynomials is the method of difference between two perfect squares, sometimes called DOTS. That gives students a different way in instead of simply average worksheets. Mixing such methods as Tic Tac Toe factoring and DOTS avoids the practice feeling boring.
Both ways convert a topic, that could be dull, into something a bit more hands on and interactive for pupils at different levels of skill.