AF 1.2 Write and evaluate an
algebraic expression for a
given situation, using up to
three variables.
Objective: Students will evaluate
algebraic expressions with like
terms using up to three variables,
by using math facts skills, writing
reflective summaries, and scoring
an 80% proficiency on exit slip.
Terms Are separated by a
sign
(- or +)
How many terms are in the
example?
Coefficient it is the number next
to the variable. You must have a
variable to have a coefficient.
Any variable without a number
in front of it has an understood
coefficient of 1.
Constant a number without a
variable
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!
Evaluate means to find the value of an
algebraic expression by substituting
numbers in for variables.
m=2
6+m?
6+2
8
Evaluate the expression if a = 3 and b = 4.
1) 3a  b
3 3  4
94
13
2) 2b  a
243
83
5
Evaluate the expression if x = 5 and y = 3.
3x
1)
y
3 5
3
15
3
5
2) x  y
2
2
5 3
25  9
2
34
2
 Step
One: Write the expression.
4x + 5x -2 - 2x + 7
 Collect
all the terms together which are alike.
Remember that each term comes with an
operation (+,-) which goes before it.
4x, 5x, and -2x -2 and 7
 Simplify
the variable terms.
4x+5x-2x = 9x-2x = 7x
 Simplify
-2+7 = 5
 You
the constant (number) terms.
have a simplified expression by writing all
of the results from simplifying.
7x + 5
Combine Like Terms
(put the same variables together!)
That is the answer…don’t do anything else!
Collect all the terms together which
are alike. Remember that each term
comes with an operation (+,-) which
goes before it.
Collect all the terms together which are
alike. Remember that each term comes
with an operation (+,-) which goes
before it.
6y + 2x + 4y + 8
Simplify the variable terms.
6y + 2x + 4y + 8
2x + 10y + 8
Collect all the terms together
which are alike. Remember that
each term comes with an operation
(+,-) which goes before it.
7n + 6y + 3 – 2n + 4
7n + 6y + 3 – 2n + 4
5n + 6y + 7
EX: 3

Collect all the terms together which are alike. Remember that
each term comes with an operation (+,-) which goes before it.
Simplify the variable terms.
r + 8y
Simplify the variable terms.
A
variable or algebraic expression is an
expression that consists of one or more
variables
numbers
________ and _________
along with one or more
operations
equal
____________.
(Note: No _______
sign)
expression
 To evaluate an expression write the _________,
substitute a number
_______ for each variable, and
simplify
_________
the result.
• In an expression, ________ terms are the
terms that have the same ________.
A coefficient is a number that is________to a
variable.
Simplify the following:
1. 5x + 3y - 6x + 4y + 3z
1.
3b - 3a - 5c + 4b
2.
4ab – 2a2b + 5 – ab + ab2 + 2a2b + 4
3.
5xy – 2yx + 7y + 3x – 4xy + 2x
4n + 9 + 6m - n - 2m + 2
4m + 3n + 11
6x + 3
9x + 8
2x +6y
11x+ 3x² +37
x² +6x + 8
12y + 6x + 24
5y + 9x +12
7x + 1
12x² +14x
15
4x
3x + y + 5
4(2m + 3) – 5
4(2m + 3) – 5
8m + 12 – 5
8m + 7
3(4c + 2n) + 4 – 2c
3(4c + 2n) + 4 – 2c
12c + 6n + 4 – 2c
10c + 6n + 4
5(x + 2) + x + 7
5(x + 2) + x + 7
5x + 10 + x + 7
6x + 17
x(4 + 7) + 4x + y
x(4 + 7) + 4x + y
4x + 7x + 4x + y
15x + y
x + 2(3x + 4y) + 3
x + 2(3x + 4y) + 3
x + 6x + 8y + 3
7x + 8y + 3
11x + y + 7
3x + 2
11x + 7y + 6
x² + 3x
5x
5x + 7y + 3
3x²
6x² + 6y -2x+3