Download Writing Equations

Writing Equations
Presented By
Mr. G. Laws
8thMath/Algebra 1
Standard(s)
Math 1 – A.CED.1- Create equations and inequalities
with one variable and use them to solve problems.
8th Grade Mathematics – 8.EE.7- Solve linear equations
in one variable.
Essential Question
O Using math principles, how can you solve
real world problems by writing and solving a
linear equation?
Writing Equations
O Writing equations is one strategy you can
use to solve linear equations or real world
problems.
O You must be able to identify the variable that
represents an unidentified number or
measure referred within the problem.
O Then you write a verbal expression as an
algebraic expression or equation.
Key Words
Addition
Subtraction Multiplication Division
Equal (=)
Plus
Increase
Sum
Add
Total
In all
More than
In addition
and
Minus
Decrease
Difference
Subtract
Less than
Is
Same as
Similar
Equal to
Decrease by
Fewer than
Per
Times
Product
Multiplied
Each
Factors
Rate
Ratio
Divided
Quotient
Separate
Writing Algebraic Expressions
O There is an important concept to remember
when writing algebraic expressions or
equations.
Write a model
of the
situation
using words.
Define the
variable
Write an
algebraic
expression or
equation
Writing Algebraic Expressions
O Write five years older than her brother as an algebraic
expression.
O Words – five years older than her brother as an algebraic
expression
O Variable –
O Let a represent her brother’s age.
O Expression –
Five years
older than
her brother’s age
5
+
a
O The expression is 5 + a
Writing Algebraic Expressions
O Write the following as an algebraic
expression.
1. 18 seconds faster than Tina’s time.
2. The difference between 7 and a number.
3. The quotient of a number and nine.
Answers:
1. t - 18
2. 7- n or n -7
3. n/9
Writing Algebraic Equations
O Write a number less than 8 is 22
O Words – a number less than 8 is 22
O Variable –
O Let n represent the number.
O Equation –
A number
less than
8
is
n
8
=
O The equation is n – 8 = 22
22
22
Writing Two Step Equations
O Write two times a number plus 10 is 65
O Words – two times a number plus 10 is 65
O Variable –
O Let n represent the number.
O Equation –
Two times a number
plus 10 is 65
2 (x)
n
+ 10 = 65
O The equation is 2n + 10 = 65
Writing Equations w/variables
on Both Sides
O Write eight plus four times a number is five times the
number.
O Words – eight plus four times a number is five times
a number.
O Variable –
O Let n represent the number.
O Equation –
eight plus four times a number is five times a number
8
+
4
(x)
n
= 5 (x)
n
O The equation is 8 + 4n = 5n
Writing Multi-Step Equations
O Translate; three times the sum of a number and
4 is 32.
O Words – three times the sum of a number and 4 is
32
O Variable –
O Let n represent the number.
O Equation –
Three times (the sum of a number and 4) is 32
3
(x)
(n+4)
= 32
O The equation is 3 ( n + 4) = 32
Using Equations to Solve Real
World Problems
O A New York taxi cab driver charges his passengers
$2.25 for each fare plus an additional $1.50 per mile
traveled. The total ride for one passenger was
$12.75. How many miles did the passenger ride in
the taxi cab?
O Write the Equation and solve :
2.25+ 1.50m = 12.75
-2.25
-2.25
--------------------------------------------1.50 m = 10.50
1.50m = 10.50
------------ ----------1.50
1. 50
m = 7 miles
Summarize/Reflect
O What do you now know about writing
expressions and equations?
O Is there anything else you would want to
learn about writing expressions or
equations?
O Can you answer the essential question to
this lesson?