Lesson 4.2 Multiplying Polynomials Objectives: • Use the BOX method to multiply polynomials Multiplying Polynomials

2x2 for a Binomial x Binomial Concept: Using the Box method Multiply: (x + 2)(x + 4) Step 1: Draw the box. (What are the dimensions?) 2x2 for a Binomial x Binomial

Concept: Using the Box method Multiply: (x + 2)(x + 4) Step 2: Set up the box I’m going to need a lot more room than this…

Concept: Using the Box method Multiply: (x + 2)(x + 4) Step 3: Multiply row by column. ………………………………………………. This part is kind of like filling in a multiplication times table.

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Concept: Using the Box method Multiply: (x + 2)(x + 4) Step 4: Combine like terms. ……………………………….. You might notice that the “like” terms kind of line up with each other diagonally.

You Rock

That’s amazing. LET’S DO THAT AGAIN! FASTER!!!

2x2 for a Binomial x Binomial Concept: Do it Again Hold on! Here we go!!! 2x2 for a Binomial x Binomial

YOU TRY What Do I Do First?????

2x2 for a Binomial x Binomial

Concept: Other Sized Polynomials Does the Box Method work with any size? YES! This is a binomial times a trinomial. What will the dimensions of the box be? 2 X 3

Concept: Other Sizes cont… 2x2 +10x –6 10x3 50x2 –30x 30x 6x2 –18 5x +3 10x3 + 50x2 + 30x + 6x2 – 30x – 18 10x3 + 56x2 – 18

Concept: You Try!!! Multiply. (x + 2)(x – 8) x2 – 6x – 16 3. (2x – 5y)(3x + y) x2 – 6x – 16 2x3 – x2 – 29x + 28 6x2 – 13xy – 5y2