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# Solving addition and subtraction equations power point copy

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• 1. Solving Addition and Subtraction Equations
• 2. An equation is a mathematical sentence that contains an
• 3. The expression on the left and right side of the equal sign are equivalent. One or both sides may contain a variable.
• 4. A variable is a letter or symbol that stands for a number.
• 5. To solve an equation, you must find what the variable represents so that the two parts are equal.
• 6. Equations are like balance scales. In order to keep a scale balanced you must have the same amount of weight on both
• 7. If I took one block away from the left side, what would I have to do to keep the scale from tipping?
• 8. If I added 6 more apples to the right side, how could I keep the scale from tipping?
• 9. To keep an equation equal, we must do exactly the same thing to each side of the equation. If we add a number to one side, we must add that same number to the other side and vice versa.
• 10. Addition and subtraction are called “inverse operations”.
• 11. Multiplicatio n and division are inverse operations, too!
• 12. for Solving Addition and Subtraction Equations
• 13. 1. Look to see what side the variable is on.
• 14. 2. Decide what operation is being shown.
• 15. 3. Do the inverse of that operation to both sides.
• 16. 4. Write what number the variable stands for
• 17. 5. Check the solution by “substituting” the number back into the equation to
• 18. Example 1 (bar model) m + 18 = 34 m 18 34 Look for variable Do the inverse What number does m represent? m = 16 Substitute in m 16 18 34 16 + 18 = 34 34 = 34 Solution is correct!
• 19. Example 1 m + 18 = 34 -18 -18 m = 16 Do the inverse m + 18 = 34 16 + 18 = 34 34 = 34 substitute in m Look for variable Write what m is Solution is correct!
• 20. Always remember to check your solution to the equation.
• 21. Example 2 68 = y + 43 -43 -43 Look for variable 25 = y 68 = y + 43 68 = 25 + 43 68 = 68 Write what y is Do the opposite Plug in y Solution is correct!
• 22. Example 3 t - 14 = 22 + 14 +14 t = 36 Do the inverse t - 14 = 22 36 - 14 = 22 22 = 22 Substitute in t Look for variable Write what t is Solution is correct!
• 23. Try These... 1. 2. 3. 4. r + 5 = 18 m - 26 = 59 102 = x - 15 a + 39 = 56 r = 13 m = 85 117 = x a = 17
• 24. Prediction: You will show all of the steps (including checking) as you have been shown today
• 25. Are there any questions about solving addition or subtraction equations?