Transcript algebraic expressionsx

basic
2+ 4 × 5 − 32 =
2+ 4 × 5 − 9
2+ 20− 9
22− 9
13
POD#1
advanced
(4 + 23 × 4) − 12 =
(4 + 8 × 4) − 12
(4 +32) − 12
(36) − 12
24
Algebraic Expressions
A variable is a symbol that represents an
unknown quantity. An algebraic
expression, such as n+2, is an expression
that contains variables, numbers, and at
least one operation.
The branch of mathematics that involves expressions
with variables is called algebra.
6d
6 times d
9st
9 times s times t
𝑚
𝑛
m divided by n
a3
a times a times a
The numerical factor of a multiplication expression that
contains a variable is called a coefficient. So, 6 is the
coefficient of 6d.
Example 1
Evaluate 2(n+3) if n= -4
2(n+3) = 2(-4+3)
=2(-1)
=-2
To translate a verbal phrase into an algebraic expression, the
first step is to define a variable. When you define a variable,
you choose a variable to represent an unknown quantity.
Example:
Leah has already read 20 pages of a book. She plans to
read 5 pages each day from now on. Write an expression
that represents the total number of pages she will have
read in d days.
20 + 5d
Whiteboard time
Evaluate 8w − 2v if w=5 and v=3
8(5) − 2(3)
40 − 6
34
Evaluate 4y3 + 2 if y=3
4(3)3 + 2
4(27) + 2
108 +2
110
An MP3 player costs $70 and song
downloads cost $0.85 each. Write an
expression that represents the cost of
the MP3 player and x number of
downloaded songs.
70 + 0.85x
An MP3 player costs $70 and song
downloads cost $0.85 each. Write an
expression that represents the cost of
the MP3 player and x number of
downloaded songs. Then find the total
cost if 20 songs are downloaded.
70 + 0.85x
70 + 0.85 (20) = $87
POD #2
basic
3 + 3 × 32 =
3+ 3 × 9
3 + 27
30
advanced
(4 + 8 ÷ 2)2 − 30 =
(4 + 4)2 − 30
(8)2 − 30
64 − 30
34
Let’s practice
Four more than a number
x+4
Let’s practice
Fifteen less than twice a number
2x − 15
Let’s practice
Three times a number, increased
by seventeen
3x + 17
Let’s practice
The product of nine and a number,
decreased by six
9x − 6
Let’s practice
An electrician charges $45 per hour
and spends $20 a day on gasoline.
Write an algebraic expression to
represent his earnings for one day.
Let x represent the number of hours
the electrician works in one day.
45x − 20
Let’s practice
A small company has $1000 to
distribute to its employees as a bonus.
How much money will each employee
get?
Let e represent the number of
employees in the company.
1000
e
Let’s practice
Jenny earns $30 a day working part
time at a supermarket. Write an
algebraic expression to represent the
amount of money she will earn in d
days.
30d
Let’s keep practicing:
Pg. 355-356 Algebraic Expressions
worksheet