Expand & Factor Linear Expressions

How the lesson starts: Expand & Factor Linear Expressions

Party goody bags
Hi there! Ava is making goody bags for her birthday party. Each bag gets some candies, call that x, plus 4 stickers. She makes 3 bags. We write that as 3 times the group x + 4. How much is inside all 3 bags?
The area model
An area model shows what's inside. The side is 3 bags. The top is split into x and 4. Multiply 3 by each part: 3 × x = 3x candies, and 3 × 4 = 12 stickers. So 3(x + 4) = 3x + 12. That's the distributive property.
Worked example: expand
Ava's cousin makes 5 bags with x candies and 7 stickers each. That's 5(x + 7). Multiply 5 by x to get 5x. Multiply 5 by 7 to get 35. So 5(x + 7) = 5x + 35. Watch out: not 5x + 7. The 5 multiplies the 7 too!