1. Multiplying Polynomials
Grade 9 Math

2. Agenda Why are we using tiles? Zero Pairs Using Algebra Tiles
Review of Adding Subtracting
Multiplying

3. Why Tiles?
“Polynomials are unlike the other “numbers” students learn how to add, subtract, multiply, and divide. They are not “counting” numbers. Giving polynomials a concrete reference (tiles) makes them real.”
David A. Reid, Acadia University

4. Zero Pairs
Called zero pairs because they are additive inverses of each other.
When put together, they cancel each other out to model zero.

5. Addition of Integers
(+3) + (+1) =
(-2) + (-1) =

6. Addition of Integers (+3) + (-1) = (+4) + (-4) =
After students have seen many examples of addition, have them formulate rules.

7. Review of Polynomials
2x x + 2
-3x x + 3

8. Subtraction of Integers Tips
Subtraction can be interpreted as “take-away.”
Subtraction can also be thought of as “adding the opposite.”
For each of the given examples, use algebra tiles to model the subtraction.
Draw pictorial diagrams which show the modeling process.

9. Multiplication of Integers
Integer multiplication builds on whole number multiplication.
Use concept that the multiplier serves as the “counter” of sets needed.
For the given examples, use the algebra tiles to model the multiplication. Identify the multiplier or counter.
Draw pictorial diagrams which model the multiplication process.

10. Multiplication of Integers
If the counter is negative it will mean “take the opposite of.” (flip-over)
(-2)(+3)
(-3)(-1)

11. More Polynomials
Represent each of the given expressions with algebra tiles.
Draw a pictorial diagram of the process.
Write the symbolic expression.
x + 4

12. Multiplying 3(X + 2) What would these one look like? 3(X – 4)

13. Product of Two Monomials
Grade 9 Math

14. Agenda Review of Multiplying Polynomials using Algebra Tiles
Multiplying two together using tiles
Using algebra
Practice

15. Multiplying 3(X + 2) What would these one look like? 3(X – 4)

16. Monomial A polynomial with one term is called a monomial.
How would we use algebra tiles to determine (3x)(4x)?

17. Coefficients How do we multiply monomials? (3x)(4x)
1) We multiply the coefficients. The coefficients are the numbers.
2) We multiply the variables: The variables are the letters.

18. Putting it all together
(3x)(4x)
1) We multiply the numbers (coefficients).
3 x 4 =12
2) We multiply the letters (variables).
(x)(x) =x2

19. Practice
(x)(3x) (2x2)(-3x)
(3x)(12x) (-3x)(-12x)
(2x2)(4x) (x2)(x)

20. Caution
x + x = DOESN’T = x2
(x)(x) = DOESN’T = 2x