1. Section 1.1 “Expressions and Variables”
Numerical expression
consists of numbers and operations
9 + 8
4 - 9
5 ÷ 2
6(10)

2. Variable
a letter used to represent one or more numbers. a y e t k s m

3. Variable expression consists of numbers, variables, and operations.
y – 7
3t + 2y
2k - 7 3m

4. To EVALUATE A VARIABLE EXPRESSION-
substitute a number for each variable, perform the operations and simplify, if necessary.
13· n
Substitute 3 for n.
13· 3
Multiply. 39

5. Evaluate the expression when n = 3.9 n 9 3 =
Substitute 3 for n.
= 3
Divide.
b. n – 1 =
3 – 1
Substitute 3 for n.
= 2
Subtract.
Evaluate the expression when y = 2.
c. 6 y =
6 2
Substitute 2 for y.
= 12
Multiply.
d. y =
2 + 4
Substitute 2 for y..
= 6
Add.

6. Verbal model
describes a problem using words as labels and using math symbols to relate the words
‘sum’
‘minus’
‘divided’
‘times’

7. Common Words and Phrases that Indicate Operations
Verbal Phrase
Expression
Addition
Sum, plus, total, more than, increased by
5 + n k + 12
Subtraction
Difference, less than, minus, decreased by
12 – p x – 12
Multiplication
Product, times, of, multiplied by
3 x (d)
(n)(w) p ∙ k
Division
Quotient, divided by, divided into
k/ ÷ r

8. Translate verbal phrases into expressions
7 less than a number n 3y b.
3 times a number y c.
the difference of a number x and the square of a number m
x – m2 d.
the sum of 12.5 and the number c c e.
the sum of 5 and the product of 6 and the number f
5 + 6f

9. Guided Practice
Text p. 7, #1-10 all
Homework
Text p. 7-8, #12-36