[tex]\displaystyle \mathtt{\int\limits \frac{3}{x^4}dx=3\int\limits \frac{1}{x^4}dx=3 \int\limits x^{-4}dx=3\cdot \frac{x^{-4+1}}{-4+1}+C=}\\ \\ \mathtt{=3\cdot \frac{x^{-3}}{-3}+C=-x^{-3}+C=- \frac{1}{x^3}+C }\\ \\ \mathtt{\int\limits \frac{3}{x^4}dx=- \frac{1}{x^3}+C}[/tex]
