1. Year 9 Maths Algebra Expressions and Equations Introduction

2. Puzzle What is the missing number? - 2= 4 In Algebra we don't use blank boxes, we use a letter (usually an x or y, but any letter is fine). So we would write: x - 2 = 4

3. What is an Expression? An expression is a group of terms that contains letters (pronumerals/variables), numbers (coefficient) with letters, number (constant) and basic operation signs +, -, × and ÷. Examples: 2x + 3y + 5 -9p + 2r, x 2 + 5x + 6, a 3 + b 3 + 3ab 2 + 3a 2 b pronumeral coefficient constant

4. What is an Equation? An equation says that two things are equal. It will have an equals sign "=" like this: x+2=6x+2=6 That equations says: what is on the left (x + 2) is equal to what is on the right (6) So an equation is like a statement "this equals that"

5. Puzzle 1 John is y years old. Jane is x years old. John is 8 years older than Jane. Q Can you write this as an algebraic equation?

6. Puzzle 2 Two numbers multiply together to make 24. They add together to make 11. Q Can you write this as an algebraic equation? Q Can you solve for the two unknown numbers?

7. More practice… 1. Two numbers multiply together to make 156. They add together to make 25. 2. Two numbers multiply together to make 249. They add together to make 86. 3. Two numbers multiply together to make 612. They add together to make 157. 4. Two numbers multiply together to make – 15. They add together to make 2. 5. Two numbers multiply together to make 8. They add together to make – 6.