1.2 Algebraic Expressions and Models

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1.2 Algebraic Expressions and Models
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In this lesson you will

• Evaluate algebraic expressions,
• Simplify algebraic expressions by combining like
  terms,
• Solve real life problems using these skills.

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A numerical expressions consists of
These are numerical expressions

• Numbers
• Operations
• Grouping symbols

These are NOT
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Exponents are used to represent repeated factors
in multiplication.
Base
Exponent
5 factors of 2
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To evaluate powers (exponents), notice
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Write the expression using exponents
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To avoid confusion, an order of operations is
needed for expression like those shown above

• First, do operations that occur within grouping
  symbols (like parentheses).
• Next, evaluate powers.
• Then, do multiplications and divisions in order
  from left to right.
• Finally, do additions and subtractions in order
  from left to right.

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Add within parentheses
Evaluate power
Multiply
Add
To help you remember the order of operations
PEMDAS (Please Excuse My Dear Aunt Sally
Parentheses, Exponents, Multiplication
Division, Addition Subtraction.
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Evaluate the expression
P E M D A S
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A Variable

• Is a letter used to represent one or more
  numbers.
• Any number used to replace a variable is a value
  of the variable.
• An expression involving variables is called an
  algebraic expression.

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Evaluate
when x -2.
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Evaluate the expression
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Writing and Evaluating a Real-Life Model
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Suppose you have 50 and are buying some movies
on DVDs that cost 15 each. Write an expression
that shows how much money you have left after
buying n movies. Evaluate the expression when n
2 and n 3.
-
Original Amount
Price per movie
Number of movies bought
Verbal Model
Original amount 50 Price per movie 15 Number
of movies bought n
Labels
When you buy 2 movies, you have 50-15(2) 20
left When you buy 3 movies, you have 50 15(3)
5 left.
50-15n
Algebraic Model
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Simplifying Algebraic Expressions
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For an expression such as 2x 3

• The 2x and 3 are called terms.

When a term is the product of a number and a
power of a variable such as
or
The number is the coefficient of the power.
Are like terms because they have the same
variable part.
and
The distributive property makes it possible to
combine like terms into a single term.
Constant terms such as 4 and 2 are also like
terms.
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Homework

• Use Book to Finish Notes
• And Complete Worksheet 1