• Written By Varsha
  • Last Modified 24-01-2023

Factorisation Formulas: Definition, Methods, Examples & Practice Questions


Factorisation Formulas: Factorisation, also known as factoring, is a process of breaking down a large number into several small numbers. When these small numbers are multiplied, we will get the actual or original number. Usually, students are introduced to the concepts of Factorisation in Grade 6.

Factorisation is one of the important methods that is used to break down an Algebraic or Quadratic Equation into a simple form. Thus, to break down the complex equation, one should be aware of Factorisation Formulas. In this article, we will provide you with all the necessary information related to different Factorisation Formulas for Polynomials, Trigonometry, Algebra, and Quadratic Equations. Students are also provided with the Factorisation Formulas PDF, which they can download from this article.

Factorisation Formulas: Definition

When an Algebraic Equation or Quadratic Equation is reduced into a simpler equation with the help of Factorisation Method, the simpler equation is treated as Product of Factors. The Product of Factors of an equation can be an Integer, Variable or Expression itself.

Factorisation Formulas

The main approach of Factorisation Method is that we won’t be expanding the brackets further.

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Factorisation Formulas for Algebraic & Quadratic Equation

Numbers can be factorised into different combinations and applying factorisation methods to numbers is easy, whereas finding the factors of an equation is a little challenging.

The numbers 1, 3, 5, and 15 are Factors of 15 as it can be divided the number 15 itself.

1 X 15 = 15
3 X 5 = 15
5 X 3 = 15
15 X 1 = 15

The same Factoring Method is applied for Polynomials, Algebraic and Quadratic equations as well. The important Polynomials, Algebra, Quadratic Equation Factorisation Formulas are given below.

Factorisation Formulas for Algebra & Quadratic Equations

(a + b)2 = a2 + 2ab + b2

(a − b)2 = a2 − 2ab + b2

(a + b)3 =a3 + b3 + 3ab(a + b)

(a – b)3 = a3 – b3 – 3ab(a – b)

(a + b)4 = a4 + 4a3b + 6a2b2 + 4ab3 + b4

(a − b)4 = a4 − 4a3b + 6a2b2 − 4ab3 + b4

(a + b + c)2 = a2 + b2 +c2 + 2ab + 2ac + 2bc

(a + b + c +…)2 = a2 + b2 + c2 + … + 2(ab+ac+bc+…)

Factorisation Formulas for Definite Numbers & Polynomials

a2 – b2 = (a + b)(a – b)

a2 + b2 = 1/2[(a + b)2 + (a – b)2]

a3 – b3 = (a – b)(a2 + ab + b2)

a3 + b3 = (a + b)(a2 – ab + b2)

a4 – b4 = (a – b)(a + b)(a2 – ab + b2)

a5 – b5 = (a – b)(a4 + a3b + a2b2 + ab3 + b4)

Except the first 2 formulas from the above list, all other comes under Factoring Cubic Polynomials Formulas as well.

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Factorisation Formulas for nth Power

an bn = (a – b)(b0an-1 + b1an-2 + …… + bn-2a1 + bn-1a0)

an + bn = (a – b)(b0an-1 – b1an-2 + …… bn-2a1 + bn-1a0)

Factorisation Formulas for Trignometry Equations

Factorisation or Factor Formula Trigonometry is given below

  • sin A+sin B = 2sin \(\frac{A+B\ }{2}\)cos\(\frac{A-B\ }{2}\)
  • sin A–sin B = 2cos \(\frac{A+B\ }{2}\)sin\(\frac{A-B\ }{2}\)
  • cos A+cos B = 2cos \(\frac{A+B\ }{2}\)cos\(\frac{A-B\ }{2}\)
  • cos A-cos B = –2sin \(\frac{A+B\ }{2}\)sin\(\frac{A-B\ }{2}\)
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Prime Factorisation

Factorisation is the process of finding factors of the given number, whether it is a Prime or Composite number. Whereas, Prime Factorisation is the process of finding Prime Factors of a given composite number. That is, the Prime Factorisation Method can be applied only for the Composite number. There are 2 methods to find Prime Factors of the number. To know everything about how to find Prime Factors of a given number click the link below.


Solved Factorisation Questions

Few solved examples using Factorisation are given below:

1. Express the following as in the form of (a+b)(a-b)
(i) a2 – 64
(ii) 20a2 – 45b2
Answer: For representing the expressions in (a+b)(a-b) form, we will have to use the following formula: a2 – b2 = (a+b)(a-b)
(i) a2 – 64 = a2 – 82 = (a + 8)(a – 8)
(ii) 20a2 – 45b2 = 5(4a2 – 9b2) = 5(2a + 3b)(2a – 3b)
2 How to Find the Factor of an equation give below
(i) 54x3y + 81x4y2
Answer: We can Factorise the expression 54x3y + 81x4y2 in the following way:
= 2 × 3 × 3 × 3 × x × x × x × y + 3 × 3 × 3 × 3 × x × x × x × x × y × y
= 3 × 3 × 3 × x × x × x × y × (2 + 3 xy)
= 27x3y (2 + 3 xy)
3. Solve the Quadratic Equation by Factorisation Method (x + y)2 – 4xy
Answer: To solve this expression, expand (x + y)2
Use the formula:
(x + y)2 = x2 + 2xy + y2
(x + y)2 – 4xy = x2 + 2xy + y2 – 4xy
= x2 + y2 – 2xy
We know, (x – y)2 = x2 + y2 – 2xy
So, factorisation of (x + y)2 – 4xy = (x – y)2

With the help of above-solved examples, you will get an idea on how to Factorise Quadratic Equations.

FAQs on Factorisation Formulas

The frequently asked questions regarding Factorisation Formulas are given below:

Q. What is the Factorisation method in Math?

A. Factorisation is the reverse of multiplying out. Complex Algebraic, Polynomials, or Quadratic Equations are broken down to simpler Equations. The simpler equation when multiplied back gives the actual equation. This process is known as Factorisation.

Q. Define Factorisation.

A. Factorisation can be defined as the resolution of an entity into factors such that when multiplied together they give the original entity.

Q. What is the first method to solve a Quadratic Equation?

A. The first method to solve a Quadratic Equation is Factoring. Followed by Factoring, we will have to apply Quadratic Formula and Complete the Square.

Q. How do you find the HCF?

A. The highest common factor (HCF) is found by multiplying all the factors of that particular number.

Now, you are provided with all the necessary information regarding Factorisation Formulas. Students can make use of NCERT Solutions provided by Embibe for your exam preparation.


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We hope this detailed article on Factorisation Formulas helps you.

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