1­3 Solving Equations
August 25, 2009
1­3 Solving Equations
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Jun 25­6:02 PM
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1­3 Solving Equations
August 25, 2009
Check Skills You'll Need
Simplify each expression:
2. 2y + 7x + y ­ 1
x + y + 2y y
­
3 3 3
5. (x + y) ­ (x ­ y)
3. 10h + 12g ­ 8h ­ 4g
6. ­(3 ­ c) ­ 4(c ­ 1)
4. 1. 5x ­ 9x + 3
Jun 25­6:17 PM
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1­3 Solving Equations
August 25, 2009
Reminder:
You can do anything you would like to an equation as long as you do it to both sides!
Example:
x + 3 = 5
­3 ­3
x = 2
Jun 25­6:39 PM
3
1­3 Solving Equations
August 25, 2009
Solving an Equation with a Variable on Both Sides
13y + 48 = 8y - 47
Jun 25­6:48 PM
4
1­3 Solving Equations
August 25, 2009
Using the Distributive Property
3x - 7(2x - 13) = 3(-2x + 9)
Jun 25­6:52 PM
5
1­3 Solving Equations
August 25, 2009
Solving a Formula for One of Its Variables
Solve this formula for the area of a trapezoid for h.
1
A = h (b
1 + b2)
2
h = 2A
b + b
1
2
Jun 25­6:55 PM
6
1­3 Solving Equations
August 25, 2009
Solving an Equation for One of Its Variables
x
x
Solve for x.
+ 1 = a
b
ab
Answer
x = a ­ b
Jun 25­7:01 PM
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1­3 Solving Equations
August 25, 2009
A dog kennel owner has 100 ft. of fencing to enclose a rectangular dog run. She wants it to be 5 times as long as it is wide. Find the dimensions of the dog run.
Step 1: Draw a diagram.
Step 2: Define your variables
Let x = the width
Let 5x = the length
Step 3: Write an equation and solve.
x + 5x + x + 5x = 100
12x = 100
x = 25/3
x = 8 1/3
Therefore 5x = 5(8 1/3) = 41 2/3
Width = 8 1/3 ft.
Length = 41 2/3 ft.
Jun 25­7:53 PM
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1­3 Solving Equations
August 25, 2009
Radar detected an unidentified plane 5000 miles away, approaching at 700 mi/hr. Fifteen minutes later an interceptor plane was dispatched, traveling at 800 mi/hr. How long did the interceptor take to reach the approaching plane?
Step 1: Understand the question.
distance for interceptor + distance for approaching plane = 5000 mi.
Step 2: Define your variables
t = time in hours for interceptor
t + 0.25 = time in hours for the approaching plane
Step 3: Write an equation and solve.
800t + 700(t + 0.25) = 5000
800t + 700t + 175 = 5000
1500t + 175 = 5000
1500t = 4825
t = 3.217 or 3 hr 13 min
Jun 25­8:36 PM
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1­3 Solving Equations
August 25, 2009
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# 29­32, 68
Jun 25­7:09 PM
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