Transcript Solving Multi-Step Equations Using the Distributive Property…

Do Now 10/5/09
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Take out HW from Friday.
 Text page 144-146, #4-40 even
Copy HW in your planner.
 Text p. 150-152, #4-42 even
In your notebook, explain how your cell phone
bill is calculated by a two-step equation? Then
use the following equation to calculate how
many minutes you went over for this month.
$0.45m + $39.99 = $55.74
Homework
Text page 144-146, #4-40 even
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4) 3
6) 8
8) 1
10) 20
12) -12
14) 21
16) 6
18) 6
20) -2
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22) Unlike terms were
combined; -3x =5; -5/3
24) y = 3x + 7; -5
26) y = 10x – 9; 2
28) 8
30) 10
32) 1.5
34) 3.5
36) 1,2,3,4
38) 1.5 hours
40) B
Objective
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SWBAT solve multi-step equations using
algebra
Equation mathematical
sentence
with an equal sign
Like a scale,
both sides must be
EQUAL in order
to be balanced.
Solving a Multi-Step Equation
How can you get the “unknown” by itself?
8x - 3x - 10 = 20
“Undo” operations by using the INVERSE (opposite)
operation to both sides of the equation.
Solving Multi-Step Equations
STEP 1STEP 2STEP 3STEP 4STEP 5STEP 6-
Use Distributive Property
Combine like terms.
“Undo” addition and/or subtraction.
“Undo” multiplication and/or division.
Solve for the variable.
Check your work.
Solving Multi-Step Equations…
Isolate the variable! Get ‘x’ by itself.
8x – 3x – 10 = 20
5x – 10 = 20
Combine like terms.
5x – 10 + 10 = 20 + 10
Add 10 to each side.
5x = 30
Simplify.
5x = 30
5
5
Divide each side by 5.
x=6
Simplify.
Check Your Work!
8x – 3x – 10 = 20
x =6
8(6) – 3(6) – 10 = 20
Are both sides equal?
Solving Multi-Step Equations
Using the Distributive Property…
Isolate the variable! Get ‘x’ by itself.
6x – 2(x – 5) = 46
6x – 2x + 10 = 46
4x + 10 = 46
Combine like terms.
Subtract 10 from each side.
4x + 10 – 10 = 46 – 10
4x = 36
4x
36
=
4
4
x= 9
Simplify.
Divide each side by 4.
Simplify.
Check Your Work!
6x – 2(x – 5) = 46
x =9
6(9) – 2(9 – 5) = 46
Are both sides equal?
Guided Practice
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1) 6x – 2x + 11 = -5
4x + 11 = -5
4x = -16
x = -4
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2) p – 17p – 6 = -38
-16p – 6 = -38
-16p = -32
p=2
Guided Practice
6x – 2(x + 11) = -6
6x + (-2x) + (-22) = -6
4x + (-22) = -6
4x = 16
x=4
“Eric the Crane”
Eric the crane migrates from Canada to
Texas. It takes Eric 14 days to travel 2500
miles. If Eric flies at an average speed of
25 miles per hour, how many hours of the
migration is Eric NOT flying?
**HINT
Write an equation to see how long Eric is not flying.
Use ‘x’ to represent the amount of time Eric is not flying.
How many hours are there in 14 days?
Distance = Rate · Time spent flying
2500 = 25 · (336 – x)
2500 = 8400 – 25x
236 hours = x
24
Homework
Text p. 150-152, #4-42 even