How do you factor x^3 + 729?

Factor ${x}^{3} + 729$
Ans: $\left(x + 9\right) \left({x}^{2} - 9 x + 81\right)$
Apply the formula: ${a}^{3} + {b}^{3} = \left(a + b\right) \left({a}^{2} - a b + {b}^{2}\right)$
${x}^{3} + 9 = \left(x + 9\right) \left({x}^{2} - 9 x + 81\right)$