factorise (a+b)cube-(a-b)cube
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8
(a+b)^3 - (a-b)^3
(a+b)^3 = a^3 + b^3 + 3a^2b + 3ab^2
(a-b)^3 = a^3 - b^3 - 3a^2b + 3ab^2
(a+b)^3 - (a-b)^3 = a^3 + b^3 + 3a^2b + 3ab^2 - a^3 + b^3 + 3a^2b - 3ab^2
= 2b^3 + 6a^2b
= 2(b^3 + 3a^2b)
= 2b(b+3a^2)
(a+b)^3 = a^3 + b^3 + 3a^2b + 3ab^2
(a-b)^3 = a^3 - b^3 - 3a^2b + 3ab^2
(a+b)^3 - (a-b)^3 = a^3 + b^3 + 3a^2b + 3ab^2 - a^3 + b^3 + 3a^2b - 3ab^2
= 2b^3 + 6a^2b
= 2(b^3 + 3a^2b)
= 2b(b+3a^2)
Answered by
4
(a+b-a+b)(a^2+b^2+2ab-a^2+b^2+a^2+b^2-2ab)
2b (3b^2+a^2)
2b (3b^2+a^2)
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