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Factorization

Factorization is a process of splitting any given polynomial into possible factors. If a polynomial can be written as the product of two or more expressions, then each expression is called the factor of the given polynomial.

If a polynomial can be written as the product of two or more expressions, then each expression is called the factor of the given polynomial.

 

Factorization Methods

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There are a number of methods followed for factorization. Some of them are as follows:

(i) Common factors

(ii) By expressing as difference of squares

(iii) By grouping

(iv) Trinomials

(v) Sum or difference of cubes


1. Taking out Common Factors

8a3 b - 6a2b2 = 2a2b (4a - 3b)

In the above expression, we are taking out the term 2a2b, since it is common to both the terms and thus we are factoring the equation to a simplified form.


2. Expressing Polynomial as Difference of Two Squares

121x2 - 25y2 = (11x)2 - (5y)2

= (11x + 5y) (11x - 5y) [Using the identity a2-b2=(a-b)(a+b)]

This is another way to simplify an equation.

Factorization Tree

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Factorization tree is more easier to understand and construct. It is very helpful in finding prime factors of a bigger number.

Let us find factors of 18, using factor tree.

Steps of construction:
  • The digit in unit's place of 18 is 8, which is an even number so is divisible by 2. So we factorize by 2
  • Check the numbers so obtained. If both the factors are prime then stop factorization
  • If any one of them is not a prime factor, then check the unit's digit of the number.
  • If the number in unit's place is not divisible by 2 then start with 3, if not with 3 then try divisibility by 5,7.
  • Follow the above steps again until we get all factors of 18 as prime factor
Factorization tree of 18:

First, place the number on top of the page.

Factorization Tree
Now, start factorizing with 2

Now, we know 9 is not a prime factor but is divisble by 3. So, further factorize it by 3

Thus, factors of 18 are 2, 3, and 3

Polynomial Factorization

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Factorization is the process to find the factors for any given polynomial. The factorization is usually the process of finding the linear polynomial for higher order polynomials.

Below you could see polynomial factorization

Solved Examples

Question 1: Factorize the given polynomial expression x2 - 5x + 6
Solution:
Given polynomial expression is x2 - 5x + 6

Factorize numerator and denominator values, we get

First factorize the numerator value, we get

(x2 - 5x + 6) = (x2 - 3x - 2x - 6)

Grouping the first two terms and second two terms, we get

= (x2 - 3x) - (2x - 6)

= x (x - 3) - 2 (x - 3)

= (x - 3) (x - 2)

The factors of the given polynomial expression is (x - 3) and (x - 2)

Answer: The final answer is (x - 3) and (x - 2)


Question 2: Factorize the given polynomial expression x2 + 5x + 4
Solution:
Given rational expression is x2 + 5x + 4

Factorize numerator and denominator values, we get

First factorize the numerator value, we get

(x2 + 5x + 4) = (x2 + 4x + x + 4)

Grouping the first two terms and second two terms, we get

= (x2 + 4x) + (x + 4)

= x (x + 4) + 1 (x + 4)

= (x + 4) (x + 1)

The factors of the given polynomial expression is (x + 4) and (x + 1)

Answer: The final answer is (x + 4) and (x + 1)


Factorization Examples

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Below are some examples for factorization

Solved Examples

Question 1: Factorize: (5a + 6b)2 - 49b2
Solution:
Let x = 5a + 6b

Then the given expression

= (x)2 - (7b)2

= (x + 7b) (x - 7b)

Re-substituting the value of x, we get

= [(5a + 6b + 7b)] [(5a + 6b) - 7b]

= (5a + 6b + 7b) (5a + 6b - 7b)

= (5a + 13b) (5a - b)

Question 2: Factorize: x2 - 73x + 72
Solution:
Given is x2 - 73x + 72

First factorize the equation, we get

(x2 - 73x + 72) = (x2 - 72x - x + 72)

Grouping the first two terms and second two terms, we get
= (x2 - 72x) - (x - 72)

= x (x - 72) - 1 (x - 72)

= (x - 72) (x - 1)

The factors of the given quadratic equation is (x - 72) and (x - 1)

Answer: The final answer is (x - 72) and (x - 1)


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