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MAT 105 · Unit 1 ALEKS · objective 1.2

Factoring Quadratics with Leading Coefficient 1

Factor x² + bx + c by finding two numbers with sum b and product c.

Standalone concept package
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Start here

Build the concept from the beginning

Starting point

No prior equation-solving skill is assumed. Arithmetic operations, variables, equality, and every new algebra decision are explained on this page.

Learning target

Factor x² + bx + c by finding two numbers with sum b and product c.

Evidence of mastery

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.
Look first, then name the mathematics

Build the visual meaning

Candidate number pairs are checked in two columns: sum equals b and product equals c, with the matching pair forming two binomial factors.
How to read this visual: A sum-product table connects a factor pair to both the middle coefficient and constant term.
  • 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
Definition in plain language

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.

Reasoning path

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.

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.

The same method in words

  1. Set the quadratic equal to zero.
  2. List factor pairs of c.
  3. Choose the pair whose signed sum is b.
  4. Write factors, apply the zero-product property, and check.
Interactive decision model

Build the reasoning, one decision at a time

Factor and solve x² + 2x − 15 = 0.

Choose this step, then check the construction.
Choose this step, then check the construction.
Choose this step, then check the construction.

The reasoning path changes as each decision is selected.

Model before practice

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 + 5x + 6 = 0

Name the goalFind numbers with sum 5 and product 6.
Choose the next moveThe pair 2 and 3 satisfies both conditions.
Carry out the mathematics(x + 2)(x + 3) = 0, so x = −2 or −3.
Check and interpretBoth roots produce zero in the original quadratic.

Solve x² − x − 12 = 0

Name the goalProduct is negative, so the factor signs differ.
Choose the next moveThe pair −4 and 3 has sum −1 and product −12.
Carry out the mathematics(x − 4)(x + 3) = 0, so x = 4 or −3.
Check and interpretExpansion returns x² − x − 12.

Solve x² − 7x + 12 = 0

Name the goalA positive product and negative sum require two negative factor constants.
Choose the next move−3 and −4 have sum −7 and product 12.
Carry out the mathematics(x − 3)(x − 4) = 0, so x = 3 or 4.
Check and interpretSubstitution verifies both positive roots.

Practice with decreasing support

Guided practice

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.

2. Solve x² − 7x + 12 = 0.

Not completed yet.
Partially completed problem

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.

Not completed yet.
Independent practice

Six problems for repetition

Solve all six. Use the specific feedback to revise a method or sign error.

1. Solve x² − 4x − 21 = 0.

2. Solve x² + 6x − 16 = 0.

3. Solve x² − 1x − 20 = 0.

4. Solve x² + 7x + 6 = 0.

5. Solve x² − 10x + 9 = 0.

6. Solve x² + 5x − 14 = 0.

Not completed yet.

Mastery and transfer

Mastery check

Demonstrate understanding

Attempt all five. At least four correct answers are required for mastery.

1. Solve x² − 10x + 24 = 0.

2. Solve x² − 3x − 40 = 0.

3. Solve x² + 6x − 27 = 0.

4. Solve x² + 14x + 40 = 0.

5. Solve x² − 13x + 22 = 0.

Not completed yet.
Unfamiliar transfer

Explain, compare, and revise

Factor x² − 2x − 35 and explain how both the product and sum determine the signs.

Write a first attempt before opening the self-check.

The record reveals exact answers and model reasoning only after the corresponding attempt or self-check has occurred.