Evaluating Expressions

Evaluating Expressions

Lesson Goals

• I can identify a VARIABLE

• I can identify an ALGEBRAIC EXPRESSION

• I can Evaluate EXPRESSIONS

Variable

A symbol, usually a letter, used to represent an unknown number or quantity.

Algebraic Expression

An expression that may contain numbers, variables, grouping symbols, and/or operations.

Examples: 2x, 5p-1, 9h + 4, 3y², 4(a +7)

Multiple Choice

What does an Algebraic Expression NOT contain?

• exponents

• grouping symbols

• equal sign

• variables

Evaluating Expressions

To evaluate an expression means to substitute the given replacement values for each variable, then simplify to find the numerical value of the expression.

a=9, b=5, c=28

• a-3

• 9-3

• 6

a=9, b=5, c=28

• 8b

• 8(5)

• 40

a=9, b=5, c=28

• a²

• 9²

• 81

x = 3

• 2x³

• 2(3)³

•  $2\cdot27$  
  

• 54

v = 9

• 3v + 17

• 3(9) + 17

• 27 + 17

• 54

q = 9 , r = 4

• 5q + r

• 5(9) + 4

• 45 + 4

• 49

f = 1, g = 6

• 2(f + g² )

• 2(1 + 6²)

• 2(1 + 36)

• 2(37)

• 74

 $x\ =\ \frac{3}{4}$  

•  $\frac{5}{12}x$  

•  $\frac{5}{12\ }\cdot\frac{3}{4}$  

•  $\frac{5}{4}\cdot\frac{1}{4}$  

•  $\frac{5}{16}$  

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