Question

Expand (a-b)3and using the expansion find (11-7)3

Answer 1

$(a - b) {}^{3} = {a}^{3} - 3ab(a - b) - {b}^{3} \\ (11 - 3) {}^{3 } = {11}^{3} - 3(11)(3)(11 - 3) - {3}^{3} \\ = 1331 - 99(8) - 27 \\ = 1331 - 792 - 27 \\ = 512$