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Lesson 5 Functions
Today you will describe a function
and express it as an equation.
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A function is a rule that pairs each input with
only one output.
Rule: Add 3
Input Output
0 31 4
2 5
5 8
9 ? 12
Equation: I + 3 = O
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Lets complete each table.
Rule: Add 8
Input Output
1 9
2
11
4
5 13
10
3
12
Rule: Multiply by 5
Input Output
0
6 30
8 40
9
20
0
45
4
Equation: I + 8 = O Equation: I x 5 = O
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For each table, write the rule and complete
the table. Then write an equation.
Rule:
Input Output
0
2 8
3 12
4 16
24
Multiply by 4
0
6
Rule:
Input Output
7 14
2
15 22
10
11 18
Equation: I x 4 = O
Add 7
9
3
Equation: I + 7 = O
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Functions can describe many situations in
you everyday life. The table below shows
late fees for an over due book.
Rules in Words
Equation
Number of days Late (d) 1 2 3 4 5
Late fee (f) 10 20 30 40 50
Write the rule in words and as an equation.Late fee equals days times ten cents.
f = 10d
A function table will often contain variables. A
variable is a letter that is used to represent an
unknown number.
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For each function table, write
the rule in words and as an
equation. Then complete the
table.
Rules in WordsEquation
Bicycles (b) 1 3 4 5
Wheels (w) 2 4 6 10
Number of wheels equals bicycles times two.
w= 2b
2
8
Rules in Words
Equation
Tricycles (t) 1 2 4 5
Wheels (w) 3 6 9 15
Number of wheels equals tricycles times three.
w= 3t
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Rules in WordsEquation
Tickets (t) 1 2 3 4
Cost in dollars (d) 7 14 28 15
Cost in dollars equals 7 times number of tickets
d = 7t
21
5
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Lesson 6
With this lesson you will generate and solve
algebraic equations that involve grouping
with parentheses.
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Parentheses () can be used to group the numbers in an equation.
The parentheses tell us which operations to do first. They are
removed after the operation inside them is performed.
Example: 6 + (2 x 9) = c
186 + = 24
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Emma: I bought 3 markers for 8 cents each
and a notebook for 10 cents.
Equation:
Answer:
Begin by asking: What can I group together by
multiplying? 3 markers for 8 centseach. (3 x 8)
(3 x 8) + 10 = x
34 cents
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Alan: I bought 4 pencils for 3 cents each and 4
pens for 6 cents each.
Equation:
Answer:
Begin by asking: What can I group together by
multiplying? 4 pencils for 3 cents (4 x 3)4 pens for 6 cents (4 x 6)
(4 x 3) + (4 x 6) = x
36 cents
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Lucy: I bought 3 calendars for 30 cents each.
One was bent, so it cost 5 cents less.
Equation:
Answer:
Begin by asking: What can I group together by
multiplying?3 calendars for 30 cents.
(3 x 30)
(3 x 30) 5 = x85 cents
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