Download Expressions

Algebra I
1.3 Write Expressions
Objective
The student will be able to:
translate verbal expressions into
math expressions and vice versa.
Vocab
• Verbal Model — a real life situation
using words as labels and using math
symbols to relate the words
• Rate — a fraction that compares two
quantities measured in different units
• Unit Rate — when the denominator
of a rate is one
An algebraic expression
contains:
1) one or more numbers or variables, and
2) one or more arithmetic operations.
Examples:
x–3
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
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
• Translating Verbal Phrases
– Examples:
• 4 less than the quantity 6 times a number n
• 3 times the sum of 7 and a number y
• The difference of 22 and the square of a number m
– Now Try This One:
• The quotient when the quantity 10 plus a number x
is divided by 2
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.
2)
m
.
r
The sum of 8 and a
The ratio of m to r
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
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
• Write an expression
– You have a ribbon that is 8 inches long
• Suppose you cut a 2in piece? What would
you do to find the remaining length??
• Suppose you cut a piece n inches? How
could you write an expression of the length
remaining??
• Find a Unit Rate
– A car travels 110 miles in 2 hours. Find the
Unit Rate
• Solve a Multi Step Problem
– Your basic monthly charge for cell
phone service is $30, which includes
300 free minutes. You pay a fee for
each extra minute you use. One
month you paid $3.75 for 15 extra
minutes. Final your total bill if you
use 22 extra minutes.