Evaluating Expressions

Evaluating Expressions with Substitution

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Sports

• We substitute player for player in sports to give breaks. In order to substitute with the best outcome, you want to make sure they play the same position.

• It is the same thing with expressions. When we substitute, we will put in a number for the letter that it is equal to. The number and the letter are playing the same position.

• Example: If x=4, we can plug 4 in anywhere we see an x.

Multiple Choice

In sports, you substitute players into different positions then they usually play.

• True

• False

Multiple Select

Select all of the options that are examples of substitution.

• 3x, x=4, so 3(4)

• 3y, x=2, so 3(2)

• 2+x, x=2, so 2+2

• 2+y, x=4, so 2+4

Substituting and Evaluating

When you are given a number to plug in a variable's place, you are able to evaluate an expression.

Example 1: 3x; x=4; would give you 3(4), which equals 12.

Example 2: 3x+2y; x=5, y=4; so 3(5)+2(4)= 15+8=23

Multiple Choice

x+2y; x=3, y=7

when you substitute and evaluate this problem, your answer is 17.

• True

• False

Order of Operations Review

You MUST use the order of operations to evaluate correctly.

Please Excuse My Dear Aunt Sally (PEMDAS)

Parenthesis, Exponents, Multiply/Divide, Add/Subtract

*Be sure to write this at the top of every problem and check off each step as you go.

*Remember Multiply/Divide are whichever you see first left to right. This is the same for add/subtract.

Order of Operations Example (PEMDAS)

Multiple Choice

Review Check: Evaluate the following when x=2 and y=3 $$x^3+2y-3$$  

• 11

• 9

• 28

Expanding Expressions

Vocabulary Review

Multiple Choice

How many terms are in this expression?

5x + 2y + 3

• 1

• 2

• 3

• 4

Multiple Choice

A number with no variable attached is called a  _____.

• coefficient
• constant
• variable
• term

Multiple Choice

The number before a variable is the _____.

• term
• constant
• coefficient
• variable

Multiple Choice

What is the coefficient of the expression below?

8 + 5x

• 8

• 0

• 5

• -5

Multiple Choice

What is the coefficient in this expression?
3x+4-2

• x
• 4
• 3x
• 3

Multiple Choice

What are the like terms in the following expression?
5a + 2b - 3a

• 5a, -3a
• 5a, 3a
• 5a, 2b
• 5a, 4

Multiple Choice

Simplify the expression: 3x + 2x

• 5x
• x
• 6x
• 5

Multiple Choice

Simplify the expression: 2x + 1 + 7x 

• 10x
• 10
• 9x + 1
• 9 + 1x

Multiple Choice

2(4 + 9w) 

• 8+9w
• 2+9
• 8+18w
• 2+9w

Multiple Choice

2(4X-7)

• 8x-14
• 8x-7
• 6x+7
• 8x+14

Multiple Choice

Factor:
12x + 9

• 3(4x + 3)
• x(12+9)
• 3(4x - 3)
• not factorable

Multiple Choice

Factor:
12x - 20

• 4x(3 - 5)
• 4(3x - 5)