Variables and Expressions

1
Numerical Expressions
LESSON 1-2 Warm Up
Lesson 1-2 Warm Up
2
Algebraic Expressions (1-2)
What is a variable? What is an algebraic
expression? How do you model an algebraic
expression?
Variable a symbol (like a letter) that can
represent one or more numbers Example x, y, ?,
?, ? Algebraic Expression a mathematical
expression (number sentence) containing one or
more variable Example To model an algebraic
expression, choose a symbols to represent one
varaible and one number (1). Example Model the
expression 5x 3.
3
Algebraic Expressions
LESSON 1-2
Additional Examples
Draw a diagram to model the expression 2x 3.
4
Algebraic Expressions (1-2)
To evaluate an algebraic expression, replace
variables with the numbers they equal (this is
called substitution) and simplify the numeric
expression using the PEMDAS (the order of
operations). Example A certain video stores
rents video games for 3 each, so it make 3 in
profit for each game rented. Fill in the
following table to find how much the store would
earn if g games were rented.

How do you evaluate an algebraic
expression?
5
Algebraic Expressions
LESSON 1-2
Additional Examples
Evaluate 8x 2 for x 3.
6
Algebraic Expressions
LESSON 1-2
Additional Examples
The cost to rent a canoe at the lake is a 6
basic fee plus 4 for each hour h the canoe is
rented. The expression for the total cost of a
canoe rental is 6 4h. Copy and complete the
table.
7
Algebraic Expressions
LESSON 1-2
Lesson Quiz
1. Write an expression for the number of months
in y years. 2. Evaluate your expression in
Exercise 1 for 7 years. 3. Evaluate 5n n 2
for n 10. 4. Evaluate 3c 5 for c 2, 4, and
6.
12y
84 months
45
1, 7, 13