1-6 Writing Expressions

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1-6 Writing Expressions
Objective (things to learn) With this section
you will need to learn how to evaluate variable
expressions.
Terms to Know
1. Variable-is a symbol or letter used to
represent a number. 2. Algebraic expression-is a
collections of numbers, variables, operations,
and grouping symbols.
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1-6 Writing Expressions
The following is a list of Algebraic expressions
and there meanings
Algebraic expressions
Meanings
15y
15 times y
7 times a, divided by b
3 times m, plus 6
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1-6 Writing Expressions
Next, lets look at how to evaluate some
algebraic expressions.
Example 1
Evaluate 3x 7y when x 4 and y 2.
Solution to evaluate this expression, simply
substitute 4 for x and 2 for y.
First, write the expression. Then substitute 4
for x and 2 for y. Simplify 3(4) and 7(2). Then
add.
4
2
SOLUTION
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1-6 Writing Expressions
Lets look at how to evaluate another algebraic
expressions.
Example 2
Evaluate x (5x - 8) when x 3.
Solution to evaluate this expression, simply
substitute 3 for each x .
Substitute 3 for x twice.
Simplify 53.
Simplify 15 - 8.
SOLUTION
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1-6 Writing Expressions
Remember, to evaluate an expression use the
following flow chart and show your work!!!!
Substitute values for variables.
Simplify the numerical expression.
Write the algebraic expression.
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1-6 Writing Expressions
Representing real life situations.
Recall the Area of a rectangle is equal to the
length times the width.
A lw
Example 3
Suppose the length of a rectangle is 12in. and
the width of the rectangle is 5in.. What is the
Area of the rectangle?
Solution
Use the formula A lw
A (12in.)(5in.)
60 sq. in.
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THE END