1-1 variables & expressions objective the student will be able to:
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1-1 Variables & Expressions
ObjectiveThe student will be able to:
translate verbal expressions into math expressions and vice versa.
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 = L x WA = 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.
Examples:
x - 3
3 • 2n4
1m
In expressions, there are many different ways to write multiplication.
1) ab 2) a • b 3) a(b) or (a)b 4) (a)(b) 5) a x b
We are not going to use the multiplication symbol
any more. Why?
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 Subtraction Multiplication Division
sum* difference* product* quotient*
increase decrease times divided
plus minus multiplied ratio
add subtract
more than less than
total
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.
12
x
Which of the following expressions represents 7 times a number decreased by 13?
1. 7x + 13
2. 7x - 13
3. 13 - 7x
4. 13 + 7x
Answer NowAnswer Now
Which one of the following expressions represents 28 less than three times a number? 1. 28 - 3x
2. 3x - 28
3. 28 + 3x
4. 3x + 28
Answer NowAnswer Now
Write a verbal expression for:
1) 8 + a.
The ratio of m to rDo you have a different way of writing these?
The sum of 8 and a
2)
m
r.
Which of the following verbal expressions represents 2x + 9?
Answer NowAnswer Now
1. 9 increased by twice a number
2. a number increased by nine
3. twice a number decreased by 9
4. 9 less than twice a number
Which of the following expressions represents the sum of 16 and five times a number?
Answer NowAnswer Now
1. 5x - 16
2. 16x + 5
3. 16 + 5x
4. 16 - 5x
baseand 3 is called the
exponent or power.103 means 10 • 10 • 10
103 = 1000
When looking at the expression 103, 10 is called the
How is it said?21
Two to the first power22
Two to the second power or two squared23
Two to the third power or two cubed2n7
Two times n to the seventh power
Which of the following verbal expressions represents x2 + 2x?
Answer NowAnswer Now
1. the sum of a number squared and twice a number
2. the sum of a number and twice the number
3. twice a number less than the number squared
4. the sum of a number and twice the number squared
Which of the following expressions represents four less than the cube of a
number?
Answer NowAnswer Now
1. 4 – x3
2. 4 – 3x
3. 3x – 4
4. x3 – 4
Evaluate.21
222
2 • 2 = 423
2 • 2 • 2 = 82n7
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 = 24353 = 5 • 5 • 5 = 125
243 ≠ 125 They are not the same!
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