.

To find the indefinite integral of the function \( f(x) = \frac{3}{x^4} \), you can rewrite it as \( f(x) = 3x^{-4} \). Then apply the power rule for integration:

\[ \int 3x^{-4} \, dx = 3 \cdot \frac{x^{-3}}{-3} + C = -x^{-3} + C \]

So, the indefinite integral is:

\[ -\frac{1}{x^3} + C \]