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Solving Word Problems w/ Algebra
Algebra
To solve for a variable you must isolate the variable by using the “inverse” operation on both sides
(what do to one side you must do to the other)
Ask yourself “How do I make something zero”
You must make both sides of the equation equal.
Example: e + 3 = 14
e +3 -3 = 14 -3 (Inverse operation)
e = 11
Example
For an equation using addition, what is the inverse operation.
t + 4 = 17
t +4 -4 = 17 -4
t = 13
For equations using subtraction, what is the inverse operation?
u -8 = 2
U – 8 +8 = 2 + 8
Addition undoes subtraction, and subtraction undoes addition.
They are INVERSE operations
Isolate
To use inverse operations on both sides of an equation so the variable is by itself on one side
Operation Inverse Operation
Addition Subtraction
subtraction addition
Multiplication Division
Division Multiplication
Dani says that the equation j + 7 = 12 and 7 + j =12 cannot be solved the same way. What would
you say?
Example
Solve h- 25 = -11
Step 1: What is the operation of the equation?
Step 2: Inverse operation?
Step 3: Isolate
Step 4: Simplify
Solve d ◦ 11 = 99
What operation is being used?
12n =48
What is Order of Operations?
Two-Step Algebraic Equations
In two step equations, you will be doing 2 different inverse operations.
First, focus on the operations that does not involve the variable.
Example: 8v+5 = 13 8v +5 -5 =13 -5
Second, focus on the operation that is associated with the variable.
Example: 8v = 8
What is the inverse operation?
8v ÷ 8 = 8 ÷ 8 v = 1
Solve
5q -50 = 25
(g-8) / 5 = -13
s/4 + 3 = 9