Factorisation

14.1 Introduction

Factorization or factoring is the process that consists of writing a number or another number as a product of several factors, usually smaller or simpler objects of the same kind.

A factor is a number that divides that the given number. 

Here we will express algebraic expressions as products of their factors or Factorization.

Like -: 5xy = 5 x X x Y.

14.2 What is Factorisation?

When we factorise an algebraic expression, we write it as a product of factors. These factors may be numbers, algebraic variables or algebraic expressions

The irreducible factor forms of 5xy and 10x are respectively, 5xy = 5 x x x y

10x = 2 x 5 x x

Regrouping may be possible in more than one ways. Suppose, we regroup the expression as: 2xy + 3x + 2y + 3. This will also lead to factors. Let us try:

2xy + 3x + 2y + 3

= 2 x x x y + 3 x x + 2 x y + 3

= x x (2y + 3) + 1 x (2y + 3)

= (2y + 3) (x + 1)

Factorisation using identities

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

(a − b)2 = a2 − 2ab + b2

(a + b) (a − b) = a2b2

14.3 Division of Algebraic Expressions

As we have learnt how to do add and subtract, multiplications with algebraic expressions.

Now we have to learn the division with algebraic expression here.

Like - :

6x3 ÷ 2x = 6x3/2x

= 2 x 3 x x x x x x/2 x x

= 3 x x x x

= 3x2

14.4 Division of Algebraic Expressions Continued (Polynomial ÷ Polynomial)

Consider (7x2 + 14x) ÷ (x + 2)

(7x2 + 14x) ÷ (x + 2) = 7x2 + 14x/x + 2

= 7x(x + 2)/x + 2

= 7x

14.5 Can you Find the Error?

Remember, when you multiply the expression enclosed in a bracket by a constant (or a variable) outside, each term of the expression has to be multiplied by the constant (or the variable).

Remember, when you square a monomial, the numerical coefficient and each factor has to be squared.

While dividing a polynomial by a monomial, we divide each term of the polynomial in the numerator by the monomial in the denominator.