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) = a2 − b2

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.