Methods of Factorisation
(i) Common factors
(ii) By expressing as difference of squares(iii) By grouping
(iv) Trinomials(v) Sum or difference of cubes
Illustrations:
Type (i) By taking out common factors from all the terms of a polynomial

Type (ii) By expressing the polynomial as the difference of two squares

= (11x + 5y) (11x - 5y) [Using the identity a2-b2=(a-b)(a+b)]
Factorise: (5a + 6b)2 - 49b2
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)