Question

Evaluate using Identities:
(a + b)^3 - (a - b)^3

Answer 1

Step-by-step explanation:

$(a + b) {}^{3} - (a - b) {}^{3} \\ = a {}^{3} + 3a {}^{2} b + 3ab {}^{2} + b {}^{3} - (a {}^{3} - 3a {}^{2} b + 3ab {}^{2} - b {}^{3} ) \\ = a {}^{3} + 3a {}^{2} b + 3ab {}^{2} + b {}^{3} - a {}^{3} + 3a {}^{2} b - 3ab {}^{2} + b {}^{3} \\ = 6a {}^{2} b + 2b {}^{3}$