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Published byEverett Richards Modified over 8 years ago
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1)Glue Standards for Unit 4 onto page 91 2) Page 93 Make the following table on the WHOLE sheet of paper :
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Solving Addition and Subtraction Equations Page 93 Notes
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Which word do you think “Equation” has a connection to?
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YOU’RE CORRECT!
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An equation is a mathematical sentence that contains an equal sign.
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The part on the left side of the equal sign has the same value as the part on the right side. One or both sides may contain a variable.
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What is a variable? A. A number that changes constantly. B. A letter or symbol that stands for a number. C. A number that varies as you move away from zero.
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YOU’RE CORRECT!
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A variable is a letter or symbol that stands for a number.
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To solve an equation, you must find what the variable represents so that the two parts are equal.
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Equations are like balance scales. In order to keep a scale balanced you must have the same amount of weight on both sides.
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If I took one block away from the left side, what would I have to do to keep the scale from tipping?
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If I added 6 more apples to the right side, how could I keep the scale from tipping?
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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.
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Addition and subtraction are called “opposite operations” because they can ‘undo’ each other.
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What are the other two opposite operations?
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Multiplication and division are opposite operations, too!
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for Solving Addition and Subtraction Equations
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1. Look to see what side the variable is on.
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2. Decide what operation is being shown.
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3. Do the opposite of that operation to both sides.
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4. Write what number the variable stands for (ex: a = 2).
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5. Check the solution by “plugging” the number back into the equation to see if the sides are equal.
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Example 1 m + 18 = 34 Look for variable -18 Do the opposite m = 16 Write what m is m + 18 = 34 16 + 18 = 34 Plug in m 34 = Solution is correct!
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If you check your solution and you do not come out with the same numbers, then your solution is not correct. Therefore, you must rework the problem.
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Always check your answers to equations. It is the only way to make sure you get a problem correct. Why miss a problem when you can get all of them correct ?
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Example 2 68 = y + 43 Look for variable -43 Do the opposite 25 = y Write what y is 68 = y + 43 68 = 25 + 43 Plug in y 68 = Solution is correct!
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Example 3 t - 14 = 22 Look for variable + 14 +14 Do the opposite t = 36 Write what t is t - 14 = 22 36 - 14 = 22 Plug in t 22 = Solution is correct!
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Try These on page 92... 1. r + 5 = 18 2. m - 26 = 59 3. 102 = x - 15 4. a + 39 = 56 r = 13 m = 85 117 = x a = 17
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Are there any questions about solving addition or subtraction equations?
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Prediction: You will show all of the steps (including checking) as you have been shown today or credit will not be given for your homework.
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Let’s do Checking for Understanding “Worksheet Time”
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