Find the anti-derivative of $LaTeX: \displaystyle f(x) = x^{3} + 7 x^{2} + 2 x + 9$ .

Using the power rule on each term gives $LaTeX: \displaystyle F(x) = \frac{x^{4}}{4} + \frac{7 x^{3}}{3} + x^{2} + 9 x + C$