Solving Equations
An equation states that two expressions are equal. Solving an equation means finding the value of the unknown (variable) that makes the equation true. We use inverse operations to isolate the variable.
What You Need to Know
Key Concept Diagram
Use inverse operations to isolate the variable: addition undoes subtraction, multiplication undoes division
Whatever you do to one side of an equation, you must do to the other side
Check your answer by substituting back into the original equation
Two-step equations require two inverse operations applied in reverse order
Key Vocabulary
Equation
A mathematical statement showing that two expressions are equal, using an = sign
Variable
A letter used to represent an unknown number, e.g. x or y
Inverse operation
The operation that undoes another: subtraction undoes addition, division undoes multiplication
Solution
The value of the variable that makes the equation true
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
Solve: x + 9 = 14
Question 2
Solve: 3x = 21
Question 3
Solve: 2x − 5 = 11
Key Concepts Summary
- ●Use inverse operations to isolate the variable: addition undoes subtraction, multiplication undoes division
- ●Whatever you do to one side of an equation, you must do to the other side
- ●Check your answer by substituting back into the original equation
- ●Two-step equations require two inverse operations applied in reverse order