1. Presented By Mr. G. Laws 8thMath/Algebra 1
Writing Equations
Presented By
Mr. G. Laws
8thMath/Algebra 1

2. 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.

3. Essential Question
Using math principles, how can you solve real world problems by writing and solving a linear equation?

4. Writing Equations
Writing equations is one strategy you can use to solve linear equations or real world problems.
You must be able to identify the variable that represents an unidentified number or measure referred within the problem.
Then you write a verbal expression as an algebraic expression or equation.

5. 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
Decrease by
Fewer than
Per
Times
Product
Multiplied
Each
Factors
Rate
Ratio
Divided
Quotient
Separate Is
Same as
Similar
Equal to

6. Writing Algebraic Expressions
There is an important concept to remember when writing algebraic expressions or equations.
Write a model of the situation using words.
Write an algebraic expression or equation
Define the variable

7. Writing Algebraic Expressions
Write five years older than her brother as an algebraic expression.
Words – five years older than her brother as an algebraic expression
Variable –
Let a represent her brother’s age.
Expression –
Five years older than her brother’s age a
The expression is 5 + a

8. Writing Algebraic Expressions
Write the following as an algebraic expression.
18 seconds faster than Tina’s time.
The difference between 7 and a number.
The quotient of a number and nine.
Answers:
t - 18
7- n or n -7
n/9

9. Writing Algebraic Equations
Write a number less than 8 is 22
Words – a number less than 8 is 22
Variable –
Let n represent the number.
Equation –
A number less than is 22
n = 22
The equation is n – 8 = 22

10. Writing Two Step Equations
Write two times a number plus 10 is 65
Words – two times a number plus 10 is 65
Variable –
Let n represent the number.
Equation –
Two times a number plus is
2 (x) n =
The equation is 2n + 10 = 65

11. Writing Equations w/variables on Both Sides
Write eight plus four times a number is five times the number.
Words – eight plus four times a number is five times a number.
Variable –
Let n represent the number.
Equation –
eight plus four times a number is five times a number
(x) n = (x) n
The equation is 8 + 4n = 5n

12. Writing Multi-Step Equations
Translate; three times the sum of a number and 4 is 32.
Words – three times the sum of a number and 4 is 32
Variable –
Let n represent the number.
Equation –
Three times (the sum of a number and 4) is 32
(x) ( n + 4 ) = 32
The equation is 3 ( n + 4) = 32

13. Using Equations to Solve Real World Problems
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 $ How many miles did the passenger ride in the taxi cab?
Write the Equation and solve :
m = 12.75
1.50 m = 10.50
1.50m = 10.50
m = 7 miles

14. Summarize/Reflect
What do you now know about writing expressions and equations?
Is there anything else you would want to learn about writing expressions or equations?
Can you answer the essential question to this lesson?