Build the concept from the beginning
No prior equation-solving skill is assumed. Arithmetic operations, variables, equality, and every new algebra decision are explained on this page.
Use inverse operations on both sides of an equation and verify the result in the original equation.
Construct the reasoning path, solve at least 4 of 5 mastery problems, and revise an unfamiliar explanation.
Essential terms
- equation
- A statement that two mathematical expressions have the same value.
- solution
- A value that makes an equation true when substituted for the variable.
- inverse operation
- An operation that reverses another operation, such as subtraction reversing addition.
- coefficient
- A numerical factor multiplying a variable.
Build the visual meaning
- Same operation
- Both sides
- Preserve equality
- Isolate x
- Check
Read the complete visual relationship as text
- Same operation
- Both sides
- Preserve equality
- Isolate x
- Check by substitution
Inverse operations undo one another. Applying the same valid operation to both sides preserves equality while removing an operation from the variable.
Why this matters
This is the logic beneath every linear-solving step, including steps people sometimes describe informally as moving a term.
See the method as a sequence
Move from left to right. Each decision prepares the next one; on a phone, follow the numbered cards from top to bottom.
The same method in words
- Identify the outermost operation acting on the variable.
- Choose its inverse operation.
- Apply that operation to both complete sides.
- Substitute the result into the original equation to check.
Build the reasoning, one decision at a time
Choose the equality-preserving path for x/3 + 4 = 9.
The reasoning path changes as each decision is selected.
Three fully explained examples
Every example identifies the goal, explains the next move, carries out the algebra, and checks or interprets the result.
Solve 5x = 35
Solve x/4 = −3
Practice with decreasing support
Practice immediately after the model
Predict first. Then use the visual relationship and reasoned feedback to check two decisions.
1. Which operation undoes adding 8?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
2. Which operation undoes multiplying by 5?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
Finish the missing step
A prompt supplies part of the reasoning. Predict the missing mathematical move before choices appear.
1. Why must the same operation be performed on both sides?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
Six problems for repetition
Solve all six. Use the specific feedback to revise a method or sign error.
1. After solving x + 6 = 14 as x = 8, what is the best check?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
2. What is the inverse of subtracting 3?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
3. What is the inverse of dividing by 4?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
4. Which step preserves 2x + 3 = 11?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
5. If a check gives 12 = 12, what does that show?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
6. If a check gives 7 = 10, what does that show?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
Mastery and transfer
Demonstrate understanding
Attempt all five. At least four correct answers are required for mastery.
1. Which is a legal equality-preserving step from x/3 = 5?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
2. Why is checking in the original equation stronger than checking only the final line?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
3. What property justifies adding the same number to both sides?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
4. What property justifies dividing both sides by the same nonzero number?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
5. Which habit best prevents sign errors?
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
Explain, compare, and revise
Explain why performing an operation on only one side usually changes the solution set.
Guided self-check
Judge the locked first attempt against every criterion. Each judgment gives revision guidance.
Model reasoning
Equal expressions remain equal only when compatible changes are made to both. From x + 2 = 7, subtracting 2 from both sides gives x = 5. Subtracting 2 only on the left creates x = 7, a different and false claim. The same operation on both complete sides preserves the original solution.
The record reveals exact answers and model reasoning only after the corresponding attempt or self-check has occurred.