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.
Factor x² + bx + c by finding two numbers with sum b and product c.
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.
- factor
- A quantity multiplied by another quantity to form a product.
- root
- A solution of an equation; for a polynomial, it makes the polynomial equal zero.
Build the visual meaning
- Sum = b
- Product = c
- Choose signs
- Factors
- Roots
Read the complete visual relationship as text
- m + n = b
- mn = c
- Choose signs
- Write factors
- Solve roots
For x² + bx + c, choose m and n so m + n = b and mn = c. Then x² + bx + c = (x + m)(x + n).
Why this matters
The sum controls the middle term while the product controls the constant 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
- Set the quadratic equal to zero.
- List factor pairs of c.
- Choose the pair whose signed sum is b.
- Write factors, apply the zero-product property, and check.
Build the reasoning, one decision at a time
Factor and solve x² + 2x − 15 = 0.
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 x² − x − 12 = 0
Solve x² − 7x + 12 = 0
Practice with decreasing support
Practice immediately after the model
Predict first. Then use the visual relationship and reasoned feedback to check two decisions.
1. Solve x² + 7x + 10 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
2. Solve x² − 7x + 12 = 0.
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. Solve x² − 5x − 6 = 0.
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. Solve x² − 4x − 21 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
2. Solve x² + 6x − 16 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
3. Solve x² − 1x − 20 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
4. Solve x² + 7x + 6 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
5. Solve x² − 10x + 9 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
6. Solve x² + 5x − 14 = 0.
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. Solve x² − 10x + 24 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
2. Solve x² − 3x − 40 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
3. Solve x² + 6x − 27 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
4. Solve x² + 14x + 40 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
5. Solve x² − 13x + 22 = 0.
Your prediction is locked so the record preserves what you thought before recognition choices appeared.
Explain, compare, and revise
Factor x² − 2x − 35 and explain how both the product and sum determine the signs.
Guided self-check
Judge the locked first attempt against every criterion. Each judgment gives revision guidance.
Model reasoning
The factors of 35 that differ by 2 are 5 and 7. A product of −35 requires opposite signs, and the sum must be −2, so use 5 and −7. Then (x + 5)(x − 7) = 0, giving x = −5 or x = 7.
The record reveals exact answers and model reasoning only after the corresponding attempt or self-check has occurred.