1. Warm Up Day 2 Unit 3A

2. Use FOIL to Simplify: 1. (x-2)(x+2) 2. (5x + 6)(5x – 6) 3. (x -3)(x+3) 4. (x-1)(x+1)

3. Answers: 1. (x-2)(x+2) = x 2 – 4 2. (5x + 6)(5x – 6) = 25x 2 – 36 3. (x -3)(x+3)= x 2 – 9 4. (x-1)(x+1) = x 2 – 1

4. This pattern is called a difference of squares. It is the difference two terms that are both perfect squares. Knowing this pattern is useful when factoring. For example: x 2 – 16 would factor to what? (x-4)(x+4)

5. Sometimes this pattern is hidden and you have to factor out a GCF first. 1. 8x 2 -32 = 8(x 2 -4)= 8(x – 2)(x + 2) 2. 3x 2 -27 = 3(x 2 -9) = 3(x – 3)(x+3)