1. Working with Unknowns Slideshow 8, Mathematics Mr. Sasaki, Room 307 Slideshow 8, Mathematics Mr. Sasaki, Room 307

2. ObjectivesObjectives

3. Purpose of Algebra What is algebra? Algebra is a system where numbers are represented by symbols. What kind of symbols? Usually letters (Latin characters) like… Of course others are used too in specific cases. Also some Greek characters are used. Why is algebra important? Algebra makes solving problems easier. We can express, compare, summarise and make decisions with algebra. We can do lots more too!

4. Unknowns and Notation In algebra, we call symbols unknowns when they represent one value (one number). At times, symbols refer to a group of numbers or all numbers. They are then called. variables We can then usually find out what the number is.

5. Algebraic Notation In Chapter 2, we will not solve many equations, just simplify expressions. 3 bananas 7 apples

6. Algebraic Notation A quarter of a cake Two-thirds of a pizza

7. Algebraic Notation Four people buy 2 bananas and 3 coconuts each. Note: An assumption is something we think is true without being told it is. Brackets are used for grouping.

8. Answers - Easy

9. Answers - Hard

10. Worded Problems Algebra is useful for modelling. A sentence looks messy compared with an algebraic expression. Example Shunya buys 4 cars and 2 buses. Represent the cost of this algebraically. We assumed all of the cars cost the same and busses cost the same.

11. Worded Problems Algebra can represent anything, not just cost. It could be any quantity or measurement. Example Note: A problem like this could be useful to test whether Minori’s footage fits on a CD or not. The inequality above should be true for a 90min CD.

12. AnswersAnswers