1. Lesson 1-3 Algebraic Expressions & Properties
Objectives: 9P4, 9P3
(Do not write)
Evaluate algebraic expressions
Use number properties to write equivalent expressions

2. Commutative Properties – (switch elements) a + b = b + a a • b = b • a
Associative Properties- (change grouping)
a + (b + c)= (a + b) + c a • (b • c) = (a • b) • c
Identity Properties- (keep same)
a + 0 = a a • 1 = a
While these properties do not seem useful, you do use them quite often without knowing it.
Example 1)Use the commutative and associative properties to write an expression
equivalent to (9x • 12y) 8z

3. Writing algebraic expressions: • translate like a foreign language
• any phrase with “than” must reverse order – less than, more than
Example 2: Write five more than the absolute value of a number
Example 3: Write 4 less than twice the sum of a number and 10

4. Evaluate: Find value of hint: follow order of operations
Example 4: Evaluate 3x + y for x = 16 and y = 6
Simplify: Reduce to lowest terms
Example 5: Simplify
3*16 + 6 54
Line flying in literally means the # 1.
2/2 =1
y/y = 1
We are using the identity property here!!

5. Example 6: -5x - 3y -5x +(-3y) Example 7: 3x + 4y 3x-(-4y)
Subtraction Theorem : a – b = a + (-b) can be used either way Write equivalent expressions
Example 6: -5x - 3y
-5x +(-3y)
Example 7: 3x + 4y
3x-(-4y)