Chapter 1.6(a) Solving for a Variable.notebook
August 29, 2016
Homework Questions???
Bellwork:
Write as a fraction:
1) 0.74
2) 3.5%
Write as a percent:
2) 5/8
4) 0.103
Solve and check your answer:
5) 3x + 6 = ­2(­2 ­ x)
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Vocabulary: Literal Equation: an equation with two or more variables. example: 3x + 8y = 12
Chapter 1.6(a) Solving for a Variable
Solve a formula for a given variable.
Formula: equation that states a rule for a relationship among quantities.
example: distance formula d = rt; distance equals rate multiplied by time.
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Example 1: Lets start by looking at the distance formula:
Working with the distance formula d = rt find the average speed of a runner who completes a the Boston Marathon (26.2 miles) in 2.4 hours. Round to the nearest tenth.
d = rt
If you are running a race you may want to use the distance and your time to calculate your average rate (speed).
To find your speed it may be helpful to rearrange the formula so that rate (r) is isolated. The process of isolating a variable is called solving for a variable.
What is the question asking us to find? What variable in the distance formula represents it?
First solve for r.
Steps for Solving for a Variable
Step 1: Locate the variable you are asked to solve for in the equation.
Step 2: Identify the operations on this variable and the order in which they are applied.
Step 3: Use inverse operations to undo operations and isolate a variable.
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Second input the information into the formula.
d = rt
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Chapter 1.6(a) Solving for a Variable.notebook
August 29, 2016
You Try 1:
Steps for Solving for a Variable
Step 1: Locate the variable you are asked to solve for in the equation.
Step 2: Identify the operations on this variable and the order in which they are applied.
Step 3: Use inverse operations to undo operations and isolate a variable.
Solve the distance formula for t. Find the time in hours that it would take to run a marathon if your average speed was 15 miles per hour. Round to the nearest tenth. Aug 20­4:42 PM
Example 2:
The formula for a person's typing speed is
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,
where s is speed in words per minutes, w is number of words, e is ht number of errors, and m is number of minutes typing. Solve for e. You Try 2:
The formula for a person's typing speed is
You Try 3:
The formula
, gives the Celsius temperature C in terms of the Fahrenheit temperature F. Transform the formula to find the Fahrenheit temperature in terms of Celsius temperature. ,
Where s is speed in words per minutes, w is number of words, e is ht number of errors, and m is number of minutes typing. Solve for m. Aug 11­4:15 PM
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Solving literal equations for a variable works the same as solving formulas for one variable.
Example 3:
Solve 2x + y = 20 for y.
Homework
P. 51­53 #3­27, 31, 35, 37 (odds)
You Try 4:
Solve 2x + y = 20 for x.
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Chapter 1.6(a) Solving for a Variable.notebook
August 29, 2016
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