Tic-Tac-Toe Factoring A graphic organizer approach to factoring 2nd degree trinomials
© D. T. Simmons, 2005
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Tic-tac-toe Factoring •
If you have been having a little bit of trouble with factoring trinomials, this graphic organizer, based on a common tic-tac-toe grid, may be just what you need.
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To get the most out of this presentation, use pencil and paper and work through the instructions slowly and carefully.
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Keep in mind that tic-tac-toe will not do the factoring for you. But it will keep everything organized so you can concentrate on the numbers.
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I hope it helps. Have fun!
© D. T. Simmons, 2005
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Step 1 •
Draw a tic-tac-toe grid with an extra box at the bottom right.
© D. T. Simmons, 2005
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Step 2 •
Arrange the three of the trinomial in the boxes as shown.
ax ax
2
2
+ bx + c c
bx
© D. T. Simmons, 2005
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Step 3 •
In the upper right box corner put the product of ax2 and c.
ax ax
2
2
+ bx + c c
ax 2 c
bx
© D. T. Simmons, 2005
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Step 4 •
Now we will put some numbers in and work through the process.
ax
© D. T. Simmons, 2005
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c
ax 2 c
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Step 4 •
•
Now we will put some numbers in and work through the process. Use the trinomial 8x2 – 14x + 3 and set it up as shown.
8 x 2 - 14x + 3 ax 2 8x2
c 3
ax 2 c 24 x 2
-14 x
© D. T. Simmons, 2005
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Step 4 •
Now we will put some numbers in and work through the process.
•
Use the trinomial 8x2 – 14x + 3 and set it up as shown.
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that the term in the upper right box is the product of the in the left and middle boxes.
© D. T. Simmons, 2005
8 x 2 - 14x + 3 ax 2 8x2
c 3
ax 2 c 24 x 2
-14 x
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Step 5 •
•
Now find a pair of factors for the value of ax2c that will add up to bx. Put these two factors into the two boxes in the right column.
8 x 2 - 14x + 3 ax 2 8x2
c 3
ax 2 c 24 x 2 -12 x -2 x -14 x
© D. T. Simmons, 2005
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Step 6 •
•
Now find a pair of factors for the middle term of the right column that will also be factors of ax2 and c. Be sure to watch the signs of the factors.
8 x 2 - 14x + 3 ax 2 8x2
c 3
ax 2 c 24 x 2
4x
-3
-12 x -2 x -14 x
© D. T. Simmons, 2005
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Step 7 •
Now do the same for the bottom term of the right column.
8 x 2 - 14x + 3 ax 2 8x2
c 3
ax 2 c 24 x 2
4x
-3
-12 x
2x
-1
-2 x -14 x
© D. T. Simmons, 2005
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Step 8 • •
Now all the boxes of the tictac-toe grid are filled in. Check that the two bottom of the first column are factors of the top term.
8 x 2 - 14x + 3 ax
2
+ bx + c
8x2
3
24 x 2
4x
-3
-12 x
2x
-1
-2 x -14 x
© D. T. Simmons, 2005
12
Step 8 • •
•
Now all the boxes of the tictac-toe grid are filled in.
8 x 2 - 14x + 3 ax
2
+ bx + c
Check that the two bottom of the first column are factors of the top term.
8x2
3
24 x 2
Do the same for the in the middle column.
4x
-3
-12 x
2x
-1
-2 x -14 x
© D. T. Simmons, 2005
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Step 9 •
The trinomial is now factored. Each pair of diagonal is a binomial.
8 x 2 - 14x + 3 ax
2
+ bx + c
8x2
3
24 x 2
4x
-3
-12 x
2x
-1
-2 x -14 x
© D. T. Simmons, 2005
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Step 9 •
•
The trinomial is now factored. Each pair of diagonal is a binomial. Here are the two factors of the trinomial: (4x – 1) (2x – 3)
8 x 2 - 14x + 3 ax
2
+ bx + c
8x2
3
24 x 2
4x
-3
-12 x
2x
-1
-2 x -14 x
© D. T. Simmons, 2005
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Step 9 •
•
The trinomial is now factored. Each pair of diagonal is a binomial. Here are the two factors of the trinomial: (4x – 1) (2x – 3) Therefore:
x
1 3 and/or x 4 2
© D. T. Simmons, 2005
8 x 2 - 14x + 3 ax
2
+ bx + c
8x2
3
24 x 2
4x
-3
-12 x
2x
-1
-2 x -14 x
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Try it. You’ll like it! That’s all folks!
© D. T. Simmons, 2005
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