Title: Lesson 1-1 Warm-Up
1Lesson 1-1 Warm-Up
- Are the following answers reasonable? Use
estimation to determine why or why - not.
- 1. 2.
3. 4.
2Using 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?
3Using 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.
4Using 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
5Using 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