Factorise : 1 + 2ab – (a2 + b2)(a) (1 – a + b) (1 – a – b)

1.	Factorise : 1 + 2ab – (a2 + b2)(a) (1 – a + b) (1 – a – b) (b) (1 + a + b) (1 – a + b) (c) (1 + a – b) (1 – a + b) (d) (1 + a – b) (1 + a + b)
Answer» (c) (1 + a - b)(a - a + b) 1 + 2ab – (a² + b²) = 1 + 2ab - a² - b² = 1 - (a² - 2ab + b²) = 1 - (a - b)² = (1 + a - b)(a - a + b)

Factorise : 1 + 2ab – (a2 + b2)(a) (1 – a + b) (1 – a – b) (b) (1 + a + b) (1 – a + b) (c) (1 + a – b) (1 – a + b) (d) (1 + a – b) (1 + a + b)

Answer»

(c) (1 + a - b)(a - a + b)

1 + 2ab – (a² + b²)

= 1 + 2ab - a² - b²

= 1 - (a² - 2ab + b²)

= 1 - (a - b)²

= (1 + a - b)(a - a + b)