Then, we have $\frac{du}{dx} = 3x^2$, or $\frac{1}{3x^2} du = dx$. Now, we can rewrite the integral as:
$$\int \frac{x^{-2}-4}{x^{3}} dx = \int \frac{1}{u} \left(\frac{1}{3x^2}\right) du = \frac{1}{3} \int \frac{1}{u} du$$
Now, we can integrate with respect to
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