 #  Start Bellwork #37  Write out the questions!  HW, red pen, book, pencil on desk.

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 Start Bellwork #37  Write out the questions!  HW, red pen, book, pencil on desk.

Solving 2-step equations Lesson 7-1 p.336

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

2-step equations  We also solved equations like this:  -4n = 12  -4n = 12divide both sides by -4  -4 -4  n = -3solution

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

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

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

Try This  15x + 3 = 48  9g + 11 = 2  -9 - y = -12 7

Try This  15x + 3 = 48x = 3  9g + 11 = 2  -9 - y = -12 7

Try This  15x + 3 = 48x = 3  9g + 11 = 2g = -1  -9 - y = -12 7

Try This  15x + 3 = 48x = 3  9g + 11 = 2g = -1  -9 - y = -12 y = 21 7

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

Try This  -a + 6 = 8

Try This  -a + 6 = 8a = -2

Agenda 1-18-11 P.A. #1 P.338 #11-25 #11-25

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