Download Open Sentences in 2 Variables 3

Open Sentences in 2
Variables
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Open Sentence:
An equation or inequality that has one or
more variables
Open sentences in 2 variables look like:
x+y=5
x + 2y < 4
We’re solving these kind today
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y = x + 5x - 3
The Solution Set of an Open
Sentence in 2 Variables is:
An ordered pair (x, y)
The X values are called the Domain
(you may be given these values)
The Y values are called the Range
(you get the y values after you plug in x)
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Example: Solve the equation if the
domain of x is: {0, 1, 2}
Procedure:
3x – 2y = 7
1. Solve for y
(get y by itself)
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REP ALL
FOR N X
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VAL ain)
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(d o
2. Substitute in x
value (domain)
3. Get y (range)
value
Another type of Problem:
Complete each ordered pair to form a
solution.
2x +3y = 12 given: (0,__),( __, 0)
Need to find Y
Need to find X
Procedure:
1. Plug in given value into equation
2. Solve for missing variable
(All you are doing is substituting)
Another Example:
A customer asks a bank teller
for $390 in travelers checks,
some are worth $50, some
are worth $20. Find all
possibilities for the number of
each type of check the
customer could receive.
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Procedure:
1. Re-read: What is the problem asking
for ?
2. Set up variables
let x = # of 50’s let y = # of 20’s
3. Set up equation
50x +20y = 390
4. Solve for y
5. Find X values –X in this problem must
be a positive whole number
Another type!
Find the value of k so that the ordered
pair satisfies the equation.
3x – y = k; (-1, 3)
Procedure:
1. Plug in ordered pair into equation
2. Solve for k
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