Download Variables and Expressions

Objective
The student will be able to:
translate verbal expressions into
math expressions and vice versa.
SOL: A.1
Designed by Skip Tyler, Varina High School
What is the area of a rectangle?
Length times Width
If the length is 3 meters and the width is 2
meters, what is the area?
A=LxW
A = 3 x 2 = 6 meters2
A, L and W are the variables. It is any
letter that represents an unknown number.
An algebraic expression
contains:
1) one or more numbers or variables, and
2) one or more arithmetic operations.
A variable is any letter that represents an unknown
number.
x–3
Examples:
3 • 2n
4
1
m
In expressions, there are many
different ways to write multiplication.
1)
2)
3)
4)
5)
ab
a•b
a(b) or (a)b
(a)(b)
axb
We are not going to use the multiplication symbol
any more. Why?
Division, on the other hand, is
written as:
x
1)
3
2) x ÷ 3
Throughout this year, you will hear many
words that mean addition, subtraction,
multiplication, and division. Complete the
table with as many as you know.
Addition Subtraction Multiplication Division
Here are some phrases you may have listed.
The terms with * are ones that are often
used.
Addition
sum*
increase
plus
add
more than
total
Subtraction
difference*
decrease
minus
subtract
less than
Multiplication Division
product*
times
multiplied
quotient*
divided
ratio
Write an algebraic expression for
1) m increased by 5.
m+5
2) 7 times the product of x and t.
7xt or 7(x)(t) or 7 • x • t
3) 11 less than 4 times a number.
4n - 11
4) two more than 6 times a number.
6n + 2
5) the quotient of a number and 12.
x
12
Which of the following expressions represents
7 times a number decreased by 13?
1.
2.
3.
4.
7x + 13
7x - 13
13 - 7x
13 + 7x
Answer Now
Which one of the following expressions
represents 28 less than three times a number?
1.
2.
3.
4.
28 - 3x
3x - 28
28 + 3x
3x + 28
Answer Now
Write a verbal expression for:
1) 8 + a.
The sum of 8 and a
2) m
r
.
The ratio of m to r
Do you have a different way of writing
these?
Which of the following verbal expressions
represents 2x + 9?
1.
2.
3.
4.
9 increased by twice a number
a number increased by nine
twice a number decreased by 9
9 less than twice a number
Answer Now
Which of the following expressions represents
the sum of 16 and five times a number?
1.
2.
3.
4.
5x - 16
16x + 5
16 + 5x
16 - 5x
Answer Now
When looking at the expression
103, 10 is called the
base
and 3 is called the
exponent or power.
103 means 10 • 10 • 10
103 = 1000
How is it said?
21
Two to the first power
22
Two to the second power or two squared
23
Two to the third power or two cubed
2n7
Two times n to the seventh power
Which of the following verbal expressions
represents x2 + 2x?
1.
2.
3.
4.
the sum of a number squared and
twice a number
the sum of a number and twice the
number
twice a number less than the number
squared
the sum of a number and twice the
number squared
Answer Now
Which of the following expressions
represents four less than the cube of a
number?
3
1. 4 – x
2. 4 – 3x
3. 3x – 4
4. x3 – 4
Answer Now
Evaluate.
21
2
22
2•2=4
23
2•2•2=8
2n7
We can’t evaluate because we don’t
know what n equals to!!
Is 35 the same as 53?
Evaluate each and find out!
35 = 3 • 3 • 3 • 3 • 3 = 243
53 = 5 • 5 • 5 = 125
243 ≠ 125
They are not the same!