Factorise :

(x² - 3x)(x² - 3x - 1) - 20

For each trinomial (quadratic expression), given below, find whether it is factorisable or not. Factorise, if possible.

(i) x² - 3x - 54

(ii) 2x² - 7x - 15

(iii) 2x² + 2x - 75

(iv) 3x² + 4x - 10

(v) x(2x - 1) - 1

Give possible expressions for the length and the breadth of the rectangle whose area is

12x² - 35x + 25.

Factorise :

9a² - (a² - 4)²