Download + 9 - Cloudfront.net

ONE STEP
EQUATIONS
Addition and
Subtraction
Expression vs Equation
Expression:
Examples:
• is a PHRASE, a sentence
fragment
• Cannot be solved
• Has no relation symbol
Equation:
• is a SENTENCE
• Has a solution
• Has a relation symbol (=)
• 2x + 4
• 3(x -5)
• 4x + 27
Examples:
• 2x + 4 = 10
• 3(x -5) = 7
• 4x + 27 = 20
Equations
Ex. 2x + 1 = 9
Solving an equation is finding the value of the
variable that makes the sentence true
Can x = 5?
2(5) + 1 = 9
10 + 1 = 9
11 = 9 No
Can x = 4?
2(4) + 1 = 9
8+1=9
9 = 9 Yes
EQUATIONS
An equation is like a balance scale because it
shows that two quantities are equal.
4 + 2 -2
6 -2
+
What you do to one side of the equation
must also be done to the other side to keep it
balanced.
ONE STEP EQUATIONS
To solve one step equations, you need to
ask three questions about the equation:
• What is the variable?
• What operation is performed on the variable?
• What is the inverse operation?
(The one that will undo what is being
done to the variable)
ONE STEP EQUATIONS
Example 1 Solve x + 4 = 12
Variable? x Operation? Add 4 Inverse
operation? Subtract
What you do
to one side of
the equation
x + 4 = 12
-4 -4
x+0 = 8
x=8
4
must also be done
to the other side
to keep it
balanced.
ONE STEP EQUATIONS
Check your answer!!!!!!
Rewrite original
equation
substituting our
answer for x
x + 4 = 12
8 + 4 = 12
12 = 12
Original
equation
Does our
answer make
the equation
true?
Yes 
ONE STEP EQUATIONS
What if my answer was x = 9?
Rewrite original
equation
substituting our
answer for x
Original
equation
x + 4 = 12
9 + 4 = 12
Does our
answer make
the equation
true?
13 = 12
No
ONE STEP EQUATIONS
Example 2 Solve x + 10 = 17
Variable? x Operation? Add 10Inverse Subtract 10
operation?
What you do
to one side of
the equation
x + 10 = 17
- 10 - 10
x + 0= 7
x=7
must also be done
to the other side
to keep it
balanced.
ONE STEP EQUATIONS
Check your answer!!!!!!
Rewrite original
equation
substituting our
answer for x
x + 10 = 17
7 + 10 = 17
17 = 17
Original
equation
Does our
answer make
the equation
true?
Yes 
ONE STEP EQUATIONS
Example 3 Solve x - 9 = 14
Variable? x Operation? Subtract 9
What you do
to one side of
the equation
x - 9 = 14
+9 +9
x - 0 = 23
x = 23
Inverse
operation?
Add 9
must also be done
to the other side
to keep it
balanced.
ONE STEP EQUATIONS
Check your answer!!!!!!
Rewrite original
equation
substituting our
answer for x
x - 9 = 14
23 - 9 = 14
14 = 14
Original
equation
Does our
answer make
the equation
true?
Yes 
ONE STEP EQUATIONS
Example 4 Solve x - 5 = 11
Variable? x Operation? Subtract 5
What you do
to one side of
the equation
x - 5 = 11
+5 +5
x - 0 = 16
x = 16
Inverse
operation?
Add 5
must also be done
to the other side
to keep it
balanced.
ONE STEP EQUATIONS
Check your answer!!!!!!
Rewrite original
equation
substituting our
answer for x
x - 5 = 11
16 - 5 = 11
11 = 11
Original
equation
Does our
answer make
the equation
true?
Yes 
TRY:
x + 6 = 11
-6 -6
x +0 = 5
x=5
Check:
x + 6 = 11
5 + 6 = 11
11 = 11 
x-7=5
+7+7
x - 0 = 12
x = 12
Check:
x-7=5
12 - 7 = 5
5=5