Lesson 1-1 Warm-Up

1
Lesson 1-1 Warm-Up

• Are the following answers reasonable? Use
  estimation to determine why or why
• not.
• 1. 2.
  3. 4.

2
Using Variables (1-1)

• variable a symbol, usually a letter , that
  stands for a number
• algebraic expression a number sentence (includes
  numbers and operation symbols) that includes at
  least one variable
• is means
• a number means a variable, like x
• words plus, more than, sum,
  increased by
• - words minus, less than,
  difference, decreased by
• x words of , times, product (We
  show multiplication by placing the factor right
  next to the variable. Example 19k means the
  product of k and 19)
• ? words divide, quotient
• Tip Write the numbers of most phrases in the
  order of the words, except more than and less
  than.
• Example 7 decreased by 3 is translated as 7
  3
• Example the quotient of 21 and 3 is translated
  as 21 3
• Example three times a number minus 6 is
  translated as 3n - 6

• What is a variable?
• What is an algebraic expression?
• How do you translate a phrase into an algebraic
  expression?

3
Using Variables (1-1) Cont.

• How do write an algebraic expression for a word
  problem?

• When you see the phrases more than and less
  than, start with the second number.
• Example 14 less than 17 means subtract 14
  from 17, so it is translated as
• 17 14
• Example 23 less than m means subtract 23 from
  m, so it is translated as
• m 23
• Example 32 less than 5 times c means subtract
  32 from 5 times c, so start
• with 5 times c, which is translated into 5c and
  subtract it from 32 5c - 32
• Example Jerry is 4 years younger than his
  brother Steve. Write an algebraic
• expression to describe Jerrys age.
• First, we have to know how old Steve is. We do
  not have an age for Steve, so we will use a
  variable
• Let S Steves age.
• Now that we have determined Steves age as S, we
  can use it to determine Jerrys age. Jerry, J,
  is 4 years younger than Steve, so
• J S - 4
• Example If Steve is 22 years old, how old is
  Jerry?
• Since we know S 22, we can substitute (replace)
  s for 22 in J S 4
• 
  J
  22 4 18
• So, Jerry is 18 years old.

4
Using Variables (1-1) Cont.

• Example Write an equation to show the total
  income from selling tickets to a school play for
  5 each.
• Equation 5 x
• Answer I 5t
• Example Write an equation for the data in the
  table.
• Define
• Answer m 20g

• How do write an algebraic expression for a
  table?

the total income
i
Define
the number of tickets sold
t

equals
m
miles traveled
g
Number of gallons

5
Using Variables
LESSON 1-1
Lesson Quiz
Write an algebraic expression for each
phrase. 1. 7 less than 9 2. the product of
8 and p 3. 4 more than twice c Define
variables and write an equation to model each
situation. 4. The total cost is the number of
sandwiches times 3.50. 5. The perimeter of a
regular hexagon is 6 times the length of one side.
9 7
8p
2c 4
Let c the total cost and s the number of
sandwiches c 3.5s
Let p the perimeter and s the length of a
side p 6s