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 Open Sentences
are sentences that lack
information.
An
open sentence
is a sentence which
contains a variable. A variable represents an unknown number and can
appear on either side of the equals sign.
Example 1:
What
number does a stand for?
5 + a = 6 + 3
A letter can be
used for an unknown number.
To solve: compute where possible
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Think:
6 + 3 = 9
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Solve:
5 + a = 9
a = 9 - 5
a = 4
|
Check:
5 + 4 = 9
6 + 3 = 9
5 + 4 = 6 + 3 |
"5 + a = 6
+3"
is an open sentence --
the variable is "a." ( a
= 4)
A
variable is
simply a letter used to represent a number that is unknown.
Example 2: Guess and
Check
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Solve:
x
+ 8 = 14
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Try 4.
4 + 8 = 14
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No, 12 does
not equal 14
|
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Try 5.
5 + 8 = 14
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No, 13 does
not equal 14
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| Try
6. 6 + 8 = 14 |
Yes, 14 = 14
So x = 6 |
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