Question

2. Simplify: (1) (x + y)3 – (x - y)3

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Answer 1

ANSWER

$(x + y) {}^{3} - (x - y) {}^{3} \\ = (x {}^{3} + y {}^{3} + 3x {}^{2} y + 3xy {}^{2} - x {}^{3} + y {}^{3} + 3x {}^{2} y - 3xy {}^{2} ) \\ = 2(y {}^{3} + 3x {}^{2} y)$