Unit 4, Day 8

Agenda

1. Number talk: Number Strings — a row of the triangle
2. Random groups — expand $(a+b{)}^4$ by hand, slowly, then compare with row 4. Then $(a+b{)}^5$ without expanding
3. Consolidate: why the triangle counts the ways each term is assembled

Things to do before our next class

• Expand $(x+2{)}^4$ using the triangle.