Answer
$F(x)$ is the antiderivative of $f(x)$.
Work Step by Step
Since $$F(x)'= \frac{1}{3}((x+13)^3)'=\frac{3}{3}(x+13)^2=((x+13)^2=f(x)$$
thus $F(x)$ is the antiderivative of $f(x)$.
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