Warm Up Write an algebraic expression for each word phrase. 1. a number x decreased by 9

1. Solving Addition and Subtraction Equations 1-3 Pre-Algebra Warm Up Write an algebraic expression for each word phrase. 1. a number x decreased by 9 2. 5 times the sum of p and 6 3. 2 plus the product of 8 and n 4. the quotient of 4 and a number c

2. Learn to solve equations using addition and subtraction.

3. 100 = 50 2 An equation uses an equal sign to show that two expressions are equal. All of these are equations. 3 + 8 = 11 r + 6 = 14 24 = x – 7 To solve an equation, find the value of the variable that makes the equation true. This value of the variable is called the solution of the equation.

4. Additional Example 1: Determining Whether a Number is a Solution of an Equation Determine which value of x is a solution of the equation. x + 8 = 15; x = 5, 7, or 23

5. Try This: Example 1 Determine which value of x is a solution of the equation. x – 4 = 13; x = 9, 17, or 27

6. Addition and subtraction are inverseoperations, which means they “undo” each other. To solve an equation isolate the variable. This means getting the variable alone on one side of the equal sign.

7. Words Numbers Algebra ADDITION PROPERTY OF EQUALITY + 4 + 4 + z + z To solve a subtraction equation, like y 15 = 7, you would use the Addition Property of Equality. You can add the same number to both sides of an equation, and the statement will still be true. 2 + 3 = 5 x = y x = y 2 + 7 = 9

8. Subtracting a smaller number from a larger number is the same as finding how far apart the two numbers are on a number line. Subtracting an integer is the same as adding its opposite.

9. Additional Example 2A: Solving Equations Using Addition and Subtraction Properties Solve. A. 10 + n = 18

10. Additional Example 2B: Solving Equations Using Addition and Subtraction Properties Solve. B. p – 8 = 9

11. Additional Example 2C: Solving Equations Using Addition and Subtraction Properties Solve. C. 22 = y – 11

12. Try This: Example 2A Solve. A. 15 + n = 29

13. Try This: Example 2B Solve. B. p – 6 = 7

14. Try This: Example 2C Solve. C. 44 = y – 23

15. Additional Example 3A A. Jan took a 34-mile trip in her car, and the odometer showed 16,550 miles at the end of the trip. What was the original odometer reading?

16. Additional Example 3B B. From 1980 to 2000, the population of a town increased from 895 residents to 1125 residents. What was the increase in population during that 20-year period?

17. Try This: Example 3A A. Isabelle earned $27 interest and now has a balance of $535 in the bank. What was her balance before interest was added?

18. Try This: Example 3B B. From June to July, the water level in a lake has increased from 472 feet to 502 feet. What was the increase in water level during that 1-month period?

19. Assignment Write the following assignment in your agenda and on the top of your paper: Lesson 1-3: #1-12 If you did not clean out your binder on Friday please do so today. File all notes and quizzes, and recycle everything else.

20. Warm-up Determine which value of x is a solution of the equation. 1.x + 9 = 17; x = 6, 8, or 26 2.x – 3 = 18; x = 15, 18, or 21 Solve. 3.a + 4 = 22 4.n – 6= 39 5. The price of your favorite cereal is now $4.25. In prior weeks the price was $3.69. Write and solve an equation to find n, the increase in the price of the cereal.

21. Assignment

22. Assignment Write the following assignment in your agenda and on the top of your paper: Lesson 1-3: #14-38 even Remember to bring me your agenda with this assignment written in it if I need to sign your agenda book.