Worked Examples - 1.5 | 5. Factorization | IB Class 10 Mathematics – Group 5, Algebra
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Interactive Audio Lesson

Listen to a student-teacher conversation explaining the topic in a relatable way.

Difference of Squares

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0:00
Teacher
Teacher

Alright class, today we're going to tackle the difference of squares. Can anyone tell me what this means?

Student 1
Student 1

Is it when we have something like `a^2 - b^2`?

Teacher
Teacher

Exactly! When we see `a^2 - b^2`, we can factor it into `(a - b)(a + b)`. For instance, how would we factor `4x^2 - 25`?

Student 2
Student 2

That's `2x^2 - 5^2`, so it would be `(2x - 5)(2x + 5)`!

Teacher
Teacher

Great job! Remember, recognizing patterns is key to factorization.

Student 3
Student 3

Can we use this method for other expressions?

Teacher
Teacher

Absolutely! It can be applied to any similar format that meets the condition of a difference of squares. Let’s summarize: Recognizing patterns simplifies the factorization.

Sum of Cubes

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0:00
Teacher
Teacher

Next, let’s move on to the sum of cubes. Does anyone know what that looks like?

Student 4
Student 4

It’s like `a^3 + b^3`, right?

Teacher
Teacher

Correct! And how do we factor this?

Student 1
Student 1

It becomes `(a + b)(a^2 - ab + b^2)`.

Teacher
Teacher

Exactly! If we take `x^3 + 8`, we can factor this as `(x + 2)(x^2 - 2x + 4)`. Can anyone tell me how we determined that?

Student 2
Student 2

We used `2` for `b` because `2^3 = 8`!

Teacher
Teacher

Well done! This is another pattern to watch for in algebra. Let’s remember to always look for these patterns.

Factoring Quadratic Trinomials

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0:00
Teacher
Teacher

Now let's delve into factoring quadratic trinomials. Who can remind us what a quadratic trinomial looks like?

Student 3
Student 3

It's something like `ax^2 + bx + c`.

Teacher
Teacher

Exactly, and how do we factor them?

Student 4
Student 4

We need to find two numbers that multiply to `c` and add to `b`.

Teacher
Teacher

Correct! Let’s apply it to `x^2 + 7x + 12`. What do we find?

Student 1
Student 1

The numbers `3` and `4` work because they multiply to `12` and add to `7`!

Teacher
Teacher

Well done! So we can express this as `(x + 3)(x + 4)`. Remember, practice makes perfect with these!

Taking Common Factors

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0:00
Teacher
Teacher

Let’s discuss the common factors. What do we mean by that?

Student 2
Student 2

It’s the largest factor that can divide all terms in the expression.

Teacher
Teacher

Exactly! For example, in `2x^3 + 6x^2 + 4x`, what would we take out?

Student 3
Student 3

It would be `2x` since it's the common factor.

Teacher
Teacher

Correct! So we factor that out and what do we get?

Student 1
Student 1

We get `2x(x^2 + 3x + 2)`.

Teacher
Teacher

Good! Now we can factor `x^2 + 3x + 2` further into `(x + 1)(x + 2)`. Excellent teamwork today!

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section focuses on worked examples of factorization, illustrating various methods and their applications.

Standard

The 'Worked Examples' section presents practical demonstrations of factorization methods, showcasing the processes of breaking down algebraic expressions into simpler factors. Through specific examples, students learn to apply techniques like taking common factors, grouping, and recognizing special product forms.

Detailed

Worked Examples in Factorization

In this section, we delve into practical applications of factorization through a series of examples. Factorization is an essential skill in algebra, allowing the simplification of expressions and the solution of equations. The examples provided here reflect different methods used in factorization:

  1. Difference of Squares: For instance, the expression 4x^2 - 25 can be recognized as a difference of squares and is factorized as (2x - 5)(2x + 5). This highlights how patterns in expressions can lead to simplifications.
  2. Sum of Cubes: Another example, x^3 + 8, illustrates how to recognize a sum of cubes, leading to the factorization (x + 2)(x^2 - 2x + 4). This provides an excellent opportunity to see how different types of polynomial forms can be manipulated.
  3. Quadratic Trinomials: The example x^2 + 7x + 12 demonstrates how to apply the trinomial factorization method by identifying two numbers that multiply to give the constant term and add up to the coefficient of the linear term, resulting in (x + 3)(x + 4).
  4. Common Factors and Grouping: In the fourth example, 2x^3 + 6x^2 + 4x, we first extract the common factor 2x, then apply trinomial factorization within the parentheses to yield the final expression of 2x(x + 1)(x + 2).

Through these examples, students learn not only to solve specific problems but also to recognize underlying patterns that can simplify their approach to algebraic manipulations.

Audio Book

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Example 1: Factorizing the Difference of Squares

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Example 1: Factorize 4𝑥2 − 25
Solution:
4𝑥2 −25 = (2𝑥)2 −5² = (2𝑥−5)(2𝑥+5)

Detailed Explanation

In this example, we are tasked with factorizing the expression 4𝑥² - 25. This expression can be recognized as a difference of squares, which has the general form a² - b². Here, a is 2𝑥 (since (2𝑥)² = 4𝑥²) and b is 5 (since 5² = 25). The difference of squares can be factorized using the formula a² - b² = (a - b)(a + b). Therefore, we substitute a and b into the formula to get (2𝑥 - 5)(2𝑥 + 5).

Examples & Analogies

Imagine you have a rectangular garden where the width is represented by 2𝑥 and the length is represented by 5. If you want to find a way to express the area of this garden that can be optimized, recognizing that you're dealing with the difference of areas can help reduce complexity, similar to breaking down this algebraic expression.

Example 2: Factorizing a Sum of Cubes

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Example 2: Factorize 𝑥3 + 8
Solution:
𝑥3 +8 = 𝑥3 +2³ = (𝑥+2)(𝑥² −2𝑥+4)

Detailed Explanation

Here, we are factorizing 𝑥³ + 8. This can be recognized as the sum of cubes, which can be expressed as a³ + b³ where a = 𝑥 and b = 2 (because 2³ = 8). The formula for factoring a sum of cubes is a³ + b³ = (a + b)(a² - ab + b²). Applying this formula, we substitute 𝑥 for a and 2 for b to arrive at (𝑥 + 2)(𝑥² - 2𝑥 + 4).

Examples & Analogies

Think of this as a situation where two friends are building a large structure, where each friend contributes a distinct but integral part, much like how different cube contributions (a and b) can create a larger combination (the total structure).

Example 3: Factorizing a Quadratic Polynomial

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Example 3: Factorize 𝑥² + 7𝑥 + 12
Find two numbers that multiply to 12 and add to 7: 3 and 4
𝑥² +7𝑥 +12 = (𝑥 +3)(𝑥 +4)

Detailed Explanation

In example three, we are looking at the quadratic expression 𝑥² + 7𝑥 + 12. To factor this, we need to find two numbers that multiply to 12 (the constant term) and add up to 7 (the coefficient of the middle term). The numbers that satisfy these conditions are 3 and 4. We can thus express the quadratic as (𝑥 + 3)(𝑥 + 4).

Examples & Analogies

Consider this as a puzzle where you need to find a pair of lockers that add up to a certain total number when combined. Just as the quantities 3 and 4 fit perfectly into the requirements for the quadratic, the right combinations work to create an effective solution.

Example 4: Factorizing by Taking Common Factors

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Example 4: Factorize 2𝑥³ + 6𝑥² + 4𝑥
Solution:
Take common factor 2𝑥:
2𝑥³ + 6𝑥² + 4𝑥 = 2𝑥(𝑥² + 3𝑥 + 2)
Factor quadratic:
𝑥² + 3𝑥 + 2 = (𝑥 + 1)(𝑥 + 2)
Therefore,
2𝑥³ + 6𝑥² + 4𝑥 = 2𝑥(𝑥 + 1)(𝑥 + 2)

Detailed Explanation

In this example, we start with the polynomial 2𝑥³ + 6𝑥² + 4𝑥. The first step is to identify and factor out the common factor, which in this case is 2𝑥. This simplifies the expression to 2𝑥(𝑥² + 3𝑥 + 2). Next, we need to factor the quadratic expression 𝑥² + 3𝑥 + 2. By finding the two numbers that multiply to 2 and add up to 3, we discover these numbers are 1 and 2. Thus, we can express the quadratic as (𝑥 + 1)(𝑥 + 2). Bringing it all together gives us the final factored form: 2𝑥(𝑥 + 1)(𝑥 + 2).

Examples & Analogies

Imagine you have several boxes of fruits with different types but with some common fruit. Pulling out that common fruit (the common factor) makes organizing and categorizing much easier. This is similar to how we simplify the expression by taking out 2𝑥.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Factorization: The process of expressing an algebraic expression as a product of its factors.

  • Difference of Squares: Expressions that can be expressed in the form a^2 - b^2.

  • Sum of Cubes: Expressions that take the form a^3 + b^3.

  • Quadratic Trinomials: Expressions that have the format ax^2 + bx + c.

  • Common Factors: Factors that are shared between terms in an expression.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • 4x^2 - 25 = (2x - 5)(2x + 5)

  • x^3 + 8 = (x + 2)(x^2 - 2x + 4)

  • x^2 + 7x + 12 = (x + 3)(x + 4)

  • 2x^3 + 6x^2 + 4x = 2x(x + 1)(x + 2)

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • To find common factors, just look and see, take out what's shared and make it easy.

📖 Fascinating Stories

  • Imagine a farmer with a field split into two: one side he plants corn, the other soy. When he counts the plants, he finds two types. Factoring helps him understand how many seeds of each he needs to plant for full harvest.

🧠 Other Memory Gems

  • To remember the cubes, think of 'Cruising in perfect squares with my Cubed friend!'

🎯 Super Acronyms

FOG

  • Factor Out Greatest first. Always look to take the largest common factor out first.

Flash Cards

Review key concepts with flashcards.

Glossary of Terms

Review the Definitions for terms.

  • Term: Factorization

    Definition:

    The process of breaking down a complex expression into simpler expressions (factors).

  • Term: Difference of Squares

    Definition:

    A specific type of factorization for expressions that can be written in the form a^2 - b^2.

  • Term: Sum of Cubes

    Definition:

    A factorization method for expressions of the form a^3 + b^3.

  • Term: Quadratic Trinomial

    Definition:

    An algebraic expression of the form ax^2 + bx + c.

  • Term: Common Factor

    Definition:

    A factor that is common to all terms in an expression.