1. Writing Expressions

2. Writing Expressions Example 1 9 + 2 = 11 10 + 2 = 12 11 + 2 = 13
Tip: When we write an expression that represents a situation, we want to find the relationship (or connection) between the two values in each row.
Reilly’s Age
Ashley’s Age 9 11 10 12 13 14 n ?
9 + 2 = 11
= 12
= 13
= 14
In this case, Ashley’s age is always two more than Reilly’s. Therefore, the expression is _______.

3. Writing Expressions Example 2 12 ÷ 12 = 1 24 ÷ 12 = 2 36 ÷ 12 = 3
Tip: When we write an expression that represents a situation, we want to find the relationship (or connection) between the two values in each row.
Eggs
Dozens 12 1 24 2 36 3 48 4 n ?
12 ÷ 12 = 1
24 ÷ 12 = 2
36 ÷ 12 = 3
48 ÷ 12 = 4
In this case, the number of dozens is equal to the number of eggs divided by 12. Therefore, the expression is ___________.

4. Writing Expressions Example 3
Tip: When we write an expression for sequences, we want to find the relationship (or connection) between the two columns.
Position
Value of Term 1 3 2 5 7 4 9 n ?
In this example, the expression isn’t so clear. So let’s guess and check to find a rule that works.
The expression is ___________.

5. Writing Expressions
Try these: Identify the expression that represents each table.
1.) )
Spike’s Age
Rusty’s Age 2 6 3 7 4 8 n ?
Field goals
Points 1 3 2 6 9 n ?
Expression: _____________
Expression: _____________

6. Writing Expressions
Try these: Identify the expression that represents each table.
1.) )
Input
Output 1 5 2 7 3 12 n ?
Input
Output 5 22 10 47 15 72 n ?
Expression: _____________
Expression: _____________

7. Writing Expressions Real-Life Example
A triangle has a base of 8 inches. The table shows the area of the triangle for different heights. Write an expression that can be used to find the area of the triangle given its height (h).
Base (in.)
(b)
Height (in.) (h)
Area (in.2) (A) 8 1 4 2 3 12 h ?