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Start Bellwork #37 Write out the questions! HW, red pen, book, pencil on desk.
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Solving 2-step equations Lesson 7-1 p.336
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2-step equations In chapter 2 we learned how to solve simple equations. For example to solve 5 + n = -8 we learned to subtract 5 from both sides of the equation like this: 5 + n = -8 -5 -5subtract 5 -5 -5subtract 5 n = -13solution n = -13solution
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2-step equations We also solved equations like this: -4n = 12 -4n = 12divide both sides by -4 -4 -4 n = -3solution
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Solving 2-step equations Now we are going to combine 2 operations in one equation. For example, let’s try 3n – 6 = 15 3n – 6 = 15 +6 +6first add 6 to both sides +6 +6first add 6 to both sides 3n = 21then divide by 3 3n = 21then divide by 3 3 3 3 3 n = 7solution n = 7solution
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Solving 2-step equations It is a good practice to check our answer. Our original equation was 3n – 6 = 15 Our solution was n = 7 If we substitute 7 for the n we get 3(7) – 6 = 15 21 - 6 = 15 15 = 15
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Another example T - 10 = -6 4 T - 10 = -6 T - 10 = -6 4 +10 +10add 10 to both sides 4 +10 +10add 10 to both sides (4)T = 4 (4)multiply both sides by 4 4 T = 16solution T = 16solution
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Try This 15x + 3 = 48 9g + 11 = 2 -9 - y = -12 7
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Try This 15x + 3 = 48x = 3 9g + 11 = 2 -9 - y = -12 7
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Try This 15x + 3 = 48x = 3 9g + 11 = 2g = -1 -9 - y = -12 7
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Try This 15x + 3 = 48x = 3 9g + 11 = 2g = -1 -9 - y = -12 y = 21 7
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Watch your signs In a problem like 5 – x = 17, remember that the coefficient of x is -1. To solve first subtract 5 like this: 5 – x = 17 -5 -5 -5 -5 (-1) -x = 12(-1)Then multiply both sides (-1) -x = 12(-1)Then multiply both sides by -1 by -1 x = -12 x = -12
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Try This -a + 6 = 8
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Try This -a + 6 = 8a = -2
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Agenda 1-18-11 P.A. #1 P.338 #11-25 #11-25
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