1. 3.1 – SOLVING EQUATIONS BY USING ADDITION AND SUBTRACTION

2. Addition Property of Equality: If the same number is added to equal numbers, the results are equal.

3. Subtraction Property of Equality: If the same number is subtracted to equal numbers, the results are equal.

4. Property of Opposites: If you add opposite numbers, you will get zero.

5. Solving Equations: Think of an equation as a balance scale. In order for the scale to remain balanced, both sides of the scale must be the same at all times.

6. Solving Equations: Think of an equation as a balance scale. What must the unknown square weigh? 12

7. Solving Equations: Think of an equation as a balance scale. What must the unknown rectangle weigh? - 2

8. Solving Equations: If you add or subtract a number from one side of the equation, the scale is no longer balanced.

9. Solving Equations: Think of an equation as a balance scale. What must the unknown square weigh? 12+2

10. Solving Equations: Think of an equation as a balance scale. What must the unknown square weigh? 12 - 2

11. Solving Equations: Therefore, if you add or subtract a number from one side of the equation, you must balance it by adding/subtracting the same number from the other side of the equation.

12. Solving Equations: When you solve an equation, you are solving for the value of the unknown variable. If you are solving for this equation, you are looking for the value of x. Get x by its itsy bitsy self.

13. Solving Equations: A positive number will become a zero when you subtract the same number. A negative number will become a zero when you add the same positive number.

14. Solving Equations: Solve this equation: how do you clear a positive 4?

15. Solving Equations: Solve this equation: subtract 4 from both sides of the equation

16. Try these: Solve this equation: how do you clear a positive 6?

17. Solving Equations: Solve this equation: how do you clear a negative 4?

18. Solving Equations: Solve this equation: add 4 from both sides of the equation

19. Try these: Solve this equation: how do you clear a negative 6?

20. Solving Equations: Solve this equation: Remember to solve for positive x, not negative x.

21. Solving Equations: Solve this equation: Remember to solve for positive x, not negative x. Subtract 4 to both sides Since x is negative, multiply both sides by negative 1

22. Try these:

23. Word Problem Equations: 1) Four more than a number is eleven. 2) Three less than a number is negative ten.