Warm up
1. When two numbers are divided, the result is called the
_______________.
2. 𝑥 5 𝑏 2 (3𝑏 3 𝑥)
3.
43
23
4.
53
32 +42
+ 72
5. 32 ÷ [2 8 − 7 ]
Correcting Homework
• Let’s correct!
• Trade with a neighbor.
• Be kind.
• Hold questions to the end… this will help us get through it faster so
we’ll have more time for homework.
• Be sure to write “C.B. _____________” with your name.
• Double check… If you were handed a paper that is not in black ink or
pencil, hand it back to its owner… They will need to redo it.
Lesson 9: Evaluating and
comparing algebraic Expressions
Expressions and Equations
New Stuff: Expressions
Vocabulary:
• Numeric expression: an expression containing only numbers and
operations
• Algebraic expression: an expression with variables and/or numbers as
well as operations (these can also be called variable expressions)
Example 1: Evaluating Algebraic Expressions
Evaluate the expression when 𝑥 = 3 and 𝑎 = 1.
3𝑥 − 4𝑥 + 𝑎𝑥
Example 2: Evaluating Algebraic Expressions
with exponents
Evaluate the expression for 𝑦 = 2 and 𝑧 = 4.
3(𝑧 − 𝑦)2 −4𝑦 3
Example 3: comparing Algebraic Expressions
Compare the expressions when 𝑎 = 4 and 𝑏 = 3.
3𝑎2 + 2𝑏 − 4𝑏 3
2𝑎2 𝑏 2
Example 4: Phone charges
A cell phone company charges a $20 monthly fee and then 45 cents per
minute. How much would the company charge for 200 minutes?
Your turn
a. 3𝑥 − 4𝑏 + 2𝑏𝑥; 𝑥 = 10, 𝑏 = 2
b. 2𝑎𝑏 − 4𝑎2 + 10; 𝑎 = −1, 𝑏 = 8
c. Compare the expressions when 𝑥 = 2 and 𝑦 = 5.
6𝑥 2 + 𝑦 3 − 3𝑥 6 8𝑥 4 − 𝑦 3
d. The lowest recorded temperature is −89.4℃ in Antarctica. The expression
9
𝐶 + 32 can be used to convert Celsius measurements to Fahrenheit. What
5
is the lowest recorded temperature in degrees Fahrenheit?