Select a suitable identity and find the following products(i) (6x + 5)

1.	Select a suitable identity and find the following products(i) (6x + 5)(6x + 6)(ii) (2b – a)(2b +c)
Answer» i) (6x + 5) (6x + 6) is in the form of (ax + b) (ax + c). (ax + b) (ax + c) = a²x² + ax(b + c) + bc (6x + 5) (6x + 6) = (6)²x² + 6x (5 + 6) + 5 × 6 = 36x² + 6x × 11 + 30 = 36x² + 66x + 30 ii) (2b – a) (2b + c) is in the form of (ax – b) (ax + c). (ax – b) (ax + c) = a²x² + ax(c – b) – cb (2b – a) (2b + c) = (2)²(b)² + 2b (c – a) – ca = 4b² + 2bc – 2ab – ca

Select a suitable identity and find the following products(i) (6x + 5)(6x + 6)(ii) (2b – a)(2b +c)

Answer»

i) (6x + 5) (6x + 6) is in the form of (ax + b) (ax + c).

(ax + b) (ax + c) = a²x² + ax(b + c) + bc

(6x + 5) (6x + 6) = (6)²x² + 6x (5 + 6) + 5 × 6

= 36x² + 6x × 11 + 30

= 36x² + 66x + 30

ii) (2b – a) (2b + c) is in the form of (ax – b) (ax + c).

(ax – b) (ax + c) = a²x² + ax(c – b) – cb

(2b – a) (2b + c) = (2)²(b)² + 2b (c – a) – ca

= 4b² + 2bc – 2ab – ca