Step 1: Simplify the integral: \[ \int \frac{1 + x^2 + x^4}{(1 - x^3)(1 + x^3)} \, dx. \] This can be solved by partial fraction decomposition.
Step 2: After simplification, the result is: \[ \frac{1}{2} \log(1+x) - \log(1-x) + C. \]
Let \( f : (0, \infty) \to \mathbb{R} \) be a twice differentiable function. If for some \( a \neq 0 \), } \[ \int_0^a f(x) \, dx = f(a), \quad f(1) = 1, \quad f(16) = \frac{1}{8}, \quad \text{then } 16 - f^{-1}\left( \frac{1}{16} \right) \text{ is equal to:}\]