1. http://www.mathslideshows.com

2. to one side of an equation, When you do something

3. you have to do exactly the same thing to the other side.

4. http://www.mathslideshows.com To solve an equation means to find every number that makes the equation true.

5. http://www.mathslideshows.com In the equation, x is the number to get 15. you add to 7

6. http://www.mathslideshows.com What is the number? 8, of course. So we would write the solution x = 8

7. http://www.mathslideshows.com In some equations, the solution is obvious.

8. http://www.mathslideshows.com But in other equations, the solution is not so obvious.

9. http://www.mathslideshows.com Many times we need a way to solve equations. Especially if there is more than one step to solve.

10. http://www.mathslideshows.com 1) Undo the addition or subtraction operation first, by using inverse operations. 2) Undo the multiplication or division operation second, by using inverse operations.

11. http://www.mathslideshows.com R EMEMBER

12. To solve any equation, you want to get the variable all by itself. You get the variable alone by using inverse operations. Inverse Operations are like Opposites.

13. I am going to show you 2 ways to solve this equation. Hard way Easy way Undo Multiplication or Division 1 st Undo Addition or Subtraction 1 st 3x + 4 = 16

14. http://www.mathslideshows.com Hard wayEasy way Undo Multiplication or Division 1 st Undo Addition or Subtraction 1 st 3x + 4 = 16 3 3 3x 3 + 4 3 = 16 3 - 4 3 - 4 3 x + 4 3 = 3 x = 12 3 x = 4 3x + 4 = 16 -4 3x = 12 3 3 x = 4

15. http://www.mathslideshows.com 1) GOAL : Get the variable on one side of the equation. 2) You always perform the same operation to both sides of an equation. 3) To undo an operation you perform its opposite operation to both sides of the equation. 4) It is easier if you undo addition or subtraction before you undo multiplication or division.

16. http://www.mathslideshows.com 2x + 4 = 10 Get the variable alone. - 4 - 4 Subtract 4 from both sides. 2x = 6 +4 and -4 cancel out __ __ 2 2 Divide both sides by 2 x = 3 Show your check. 2(3) +4 = 10 Finish your check. 6 + 4 = 10 10 = 10 2 divided by 2 cancel to 1

17. http://www.mathslideshows.com 3m - 10 = 17 Get the variable alone. + 10 +10 Add 10 to both sides. 3m = 27 +10 and -10 cancel out __ __ 3 3 Divide both sides by 3 m = 9 Show your check. 3(9) – 10 = 17 Finish your check. 27 – 10 = 17 17 = 17 3 divided by 3 cancel to 1

18. http://www.mathslideshows.com – 4 = 8 Get the variable alone. 3 ( ) = 3 12 Multiply both sides by 3. x = 36 3 divided by 3 cancel to 1 x3x3 x3x3 +4 +4 Add 4 to both sides. x3x3 = 12 + 4 and -4 cancel out. – 4 = 8 36 3 12 – 4 = 8 8 = 8 Show your check. Finish your check.

19. http://www.mathslideshows.com + 6 = 14 Get the variable alone. 2 ( ) = 2 8 Multiply both sides by 2. x = 16 2 divided by 2 cancel to 1 x2x2 x2x2 - 6 - 6 Subtract 6 from both sides. x2x2 = 8 + 6 and -6 cancel out. + 6 = 14 16 2 8 + 6 = 14 14 = Show your check. Finish your check.

20. http://www.mathslideshows.com What Operation Do You Do? 1) 3x + 8 = 24 Subtract 8 2) 5x - 10 = 19 Divide by 3 FIRST SECOND Add 10 Divide by 5 3) x - 4 = 20 2 Add 4Multiply by 2 4) - 30 = -5x + 5 Subtract 5 Divide by -5

21. http://www.mathslideshows.com

23. Think about what you need to do to isolate the variable. Get rid of addition or subtraction first. Second get rid of multiplication or division.

24. http://www.mathslideshows.com The End! Take out your study guide !

25. http://www.mathslideshows.com 1) Undo the addition or subtraction operation first, by using inverse operations. 2) Undo the multiplication or division second, by using inverse operations. #11

26. http://www.mathslideshows.com 2 Step Subtract/Multiply Equation 3m - 10 = 17 Get the variable alone. +10 +10 Add 10 to both sides. 3m = 27 +10 and -10 cancel out __ __ 3 3 Divide both sides by 3 m = 9 #12 Show your check. 3(9) – 10 =17 Finish your check. 27 – 10 =17 17 =17 3 divided by 3 cancel to 1

27. http://www.mathslideshows.com + 6 = 14 Get the variable alone. ( ) = 8 Multiply both sides by 2. x = 16 2 divided by 2 cancels out x2x2 x2x2 - 6 - 6 Subtract 6 from both sides. x2x2 = 8 #13 + 6 and -6 cancel out. + 6 = 14 16 2 8 + 6 = 14 14 = Show your check. Finish your check. 22

28. http://www.mathslideshows.com TEACHER NOTE : Use the following slides the next day when correcting homework.

29. http://www.mathslideshows.com HOMEWORK EXPLANATION

30. An Equation is like a balance scale. Everything must be equal on both sides. 20 2x +5 =

31. http://www.mathslideshows.com 20 2x +5 = What you do to one side of an equation, you must do to the other side to keep it balanced! -5

32. http://www.mathslideshows.com 15 2x = What you do to one side of an equation, you must do to the other side to keep it balanced! __ 2 __ 2

33. http://www.mathslideshows.com 7.5 x = What you do to one side of an equation, you must do to the other side to keep it balanced!

34. http://www.mathslideshows.com Try to solve this subtraction equation 18 n - 3 = How do you get n all by itself? +3

35. http://www.mathslideshows.com Try to solve this subtraction equation 21 n = How do you get n all by itself?

36. http://www.mathslideshows.com Show your check by substituting your answer back into the original equation. 18 n - 3 = 21

37. http://www.mathslideshows.com Try to solve this division equation x3x3 15 = How do you get x all by itself? 3 3

38. http://www.mathslideshows.com Try to solve this division equation x 45 = How do you get x all by itself?

39. http://www.mathslideshows.com SHOW YOUR CHECK! x3x3 15 = 45

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