\[ \int \frac {x^6}{\sqrt {16-x^4}} \, dx \]
Optimal antiderivative \[ \frac {96 \EllipticE \left (\frac {x}{2}, i\right )}{5}-\frac {96 \EllipticF \left (\frac {x}{2}, i\right )}{5}-\frac {x^{3} \sqrt {-x^{4}+16}}{5} \]
command
integrate(x^6/(-x^4+16)^(1/2),x, algorithm="fricas")
Fricas 1.3.8 (sbcl 2.2.11.debian) via sagemath 9.6 output
\[ -\frac {{\left (x^{4} + 48\right )} \sqrt {-x^{4} + 16}}{5 \, x} \]
Fricas 1.3.7 via sagemath 9.3 output
\[ {\rm integral}\left (-\frac {\sqrt {-x^{4} + 16} x^{6}}{x^{4} - 16}, x\right ) \]