Lesson 5 – Functions

8/9/2019 Lesson 5 Functions

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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:


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:


multiplying?3 calendars for 30 cents.

(3 x 30)

(3 x 30) 5 = x85 cents

Lesson 5 – Functions

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