Question

Factorise these....plz

Answer 1

19.

Given equation is a^2 + 2ab + b^2 - 9c^2

= > (a + b)^2 - 9c^2

= > (a + b)^2 - (3c)^2

We know that a^2 - b^2 = (a + b)(a - b)

= > (a + b + 3c)(a + b - 3c)

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(21)

Given equation is (a + b)^3 - a - b

= > (a + b)^3 - (a + b)

= > (a + b )[(a + b)^2 - 1)]

= > (a + b)[(a + b)^2 - (1)^2)]

= > (a + b)[(a + b + 1)(a + b - 1)]

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

Hope this helps!