Learning Target: I can evaluate algebraic expressions for specific values of variables.
What is an Algebraic Expression?
•
An expression consists of a combination of numbers, operation symbols, and grouping
symbols such as parentheses ( ). An algebraic expression is an expression that
contains
, but NO
!
•
Expressions:
3+4
6–2
(6 + 3) -1
Algebraic Expressions
3 (c + 8)
2a
9–x
What is a variable?
A variable…
•
•
•
Is a
that represents an unknown number.
Can be any letter.
When the same letter is used more than once it represents the
The parts of an expression separated by the operation symbols are known as
•
•
•
Terms may have a
.
Variables may have a
.A
variable.
Terms without a variable are known as
.
is a number getting multiplied by a
.
Let’s Try! Given the expression below:
•
•
•
•
How many terms are in the expression?
Underline each coefficient.
Circle each constant.
Put a box around each variable
5x + 3 – 2x
Evaluating Algebraic Expressions
How do you think this is done? For example, if you are given the expression r + 5 and I tell you
that r = 5, what steps would you take?
Steps
1.)
2.)
3.)
Remember!
In expressions, there are many different
ways to write multiplication:
1)
ab
2)
a•b
3)
a(b) or (a)b
4)
(a)(b)
5)
axb
We are not going to use the multiplication symbol any more. Why?
Division, on the other hand, is written as:
𝑥
1) 3
2) x ÷ 3
Evaluate each expression when a = 12
1) a + 3
2) 17 – a
Evaluate the following when n = 4
1) 9n
2) 40 / n
Now, let’s try two operations!
1.) 7x + 4 for x = 6
2.) 8y – 22 for y = 9
3.)
12
𝑥
+ 8 for 4
4.) y + 3z for y = 5 and z = 6
Learning Target: I can translate written phrases into algebraic expressions.
When solving real-world problems, you will need to translate words, or verbal expressions, into
algebraic expressions.
In order to translate a phrase into an algebraic expression, we must first review some synonyms
for the basic operations.
Remember:

Multiplication expressions should be written in side-by-side form, with the number
always in front of the variable.
3a

2t
1.5c
0.4f
Division expressions should be written using the fraction bar instead of the traditional
division sign.
𝑥
8
Sample Phrases
Addition phrases:
• 3 more than a number t
• the sum of 10 and a number
• a number increased by 4.5
Subtraction phrases:
• a number y decreased by 4
• the difference between 10 and a number
• 6 less than a number
Multiplication phrases:
• the product of 3 and a number
• twice the number n
• 4.2 times a number p
Division phrases:
• the quotient of 25 and a number
• the number y divided by 2
• 2.5 divide g
Write an algebraic expression for:
1) m increased by 5
2) 8 less than a number x
3) a number r divided by 15
4)
27 times the sum of x and t
5)
11 less than 4 times a number y
6)
two more than 6 times a number
Write a verbal expression for:
1)
8+a
2) 3(x)
3) 2x + 9