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An expression is NOT an equation
because it DOES NOT have an equal sign.
There are 2 types of expressions.
5 + 84 Numerical
3x + 10 Algebraic
Notice there are no equal signs in these
expressions so they are not equations!
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A numerical expression contains only
numbers and symbols and NO LETTERS.
5 times 3 plus 8
(5•3) + 8
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An algebraic expression contains
only numbers, symbols, and
variables. It is sometimes referred
to as a variable expression.
The product of 3 and x
The sum of m and 8
The difference of r and 2
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3x
m+8
r-2
What is a variable?
A variable represents an unknown value.
1) 4 + x
2) 10 –
3) 5y
4) 20
?
A variable can be any letter of the
alphabet since it represents an unknown.
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Word Phrases for multiplication are:
The product of 5 and a number c
5 • c or 5c
Seven times a number t
7 • t or 7t
6 multiplied by a number d
6 • d or 6d
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The Placement rule for multiplication is:
The product of 5 and a number c
5 • c or 5c
Seven times a number t
7 • t or 7t
6 multiplied by a number d
6 • d or 6d
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Always
write the
variable
AFTER the
number.
Evaluate means to find the value of an
algebraic expression by substituting
numbers in for variables.
m=2
6+m?
6+2
8
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Evaluate means to find the value of an
algebraic expression by substituting
numbers in for variables.
r=3
7+r?
7+3
10
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Evaluate the variable expression when n = 6.
1) n  8
2) n  2
68
62
4
14
Evaluate just means solve by substitution.
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Evaluate the variable expression when n = 6.
n
4)
6
6
6
1
3) 3n
3 6
18
Evaluate just means solve by substitution.
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Evaluate the algebraic expression when n = 8.
2) 20  n
56
1)
n
20  8
56
8
12
7
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Evaluate the expression if a = 3 and b = 4.
1) 3a  b
2) 2b  a
243
83
3 3  4
94
13
5
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Evaluate the expression if a = 3 and b = 4.
3) 2ab
4) 5  ab
2  3 4
64
5  3 4
5  12
24
17
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Evaluate the expression if x = 5 and y = 3.
3x
1)
y
2) x  y
2
2
5 3
25  9
2
35
3
15
3
5
34
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2
Take Out Your Study Guide!!!
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#1
TYPES OF EXPRESSIONS
An expression is NOT an equation because it
does not have an equal sign. There are 2 types
of expressions.
NUMERICAL EXPRESSION: Contains only numbers and
symbols. Example: 5 • 3 + 4
ALGEBRAIC EXPRESSION: Contains numbers,
symbols, and variables. Also known as a
variable expression. Example: m + 8
A VARIABLE is a letter or symbol that represents a
number. Example: x
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#2
Evaluate if x = 3 and y = 4
2 x  y
2(3  4)
2
2(7)
2(49)
98
2
2
Evaluate means solve.
Show the substitution.
Show your work down.
Circle your answer.
Show your work one step at a
time down. No equal signs!
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