One of my favorite math concepts!!

 How do you solve this:  5x 2 (3x + 7)Distribute!! 15x x 2  How about this one:  (3x + 7)(x 2 + x – 4)Distribute!!! 3x 3 + 3x 2 – 12x + 7x 2 + 7x – 28Combine like terms 3x x 2 – 5x - 28

 We are going to do the same thing, but the problems look a little different.  How do we handle this: (x – 5)(x + 2)  We still distribute, but we need a way to keep track of what we did.  FOIL helps you keep track of the multiplication. This is the order: F – First Terms O – Outer Terms I – Inner Terms L – Last Terms

(x – 5)(x + 2) x 2 First Terms (x – 5)(x + 2) 2x Outer Terms (x – 5)(x + 2) -5x Inner Terms (x – 5)(x + 2) -10 Last Terms Put it together: x 2 + 2x – 5x – 10 Combine like Terms: x 2 - 3x - 10

 Remember this is just a way to keep track of your multiplication.  First Terms  Outer Terms  Inner Terms  Last Terms  Then, combine like terms.

 Watch me one more time. (x – 7)(2x + 3) F2x 2 O3x I-14x L-21 Combine like terms 2x 2 – 11x x 2 + 3x – 14x - 21

 Give these a try. You can check with your neighbors to see if you are right. 1. (x – 5)(x – 4)2. (x + 6)(x + 2) 3. (x – 3)(x + 2)4. (2x – 7)(x – 4) 5. (3x – 7)(x + 4)6. (3x – 4)(2x + 8)

 Did you get them right?? 1. x 2 – 9x x 2 + 8x x 2 – x – x 2 – 15x x 2 + 5x – x x -32

 How did you do?  Hope it was great!  Tomorrow we will review everything we have done so far and take a quiz!!!