Упростите выражение (8a^3+36a)/(a^3+27)-(4a^2)/(a^2-3a+9).

\[\frac{8a^{3} + 36a}{a^{3} + 27} - \frac{4a^{2}}{a^{2} - 3a + 9} =\]

\[= \frac{8a^{3} + 36a}{(a + 3)\left( a^{2} - 3a + 9 \right)} - \frac{4{a^{2}}^{\backslash a + 3}}{a^{2} - 3a + 9} =\]

\[= \frac{8a^{3} + 36a - 4a^{3} - 12a^{2}}{(a + 3)\left( a^{2} - 3a + 9 \right)} =\]

\[= \frac{4a^{3} - 12a^{2} + 36a}{(a + 3)\left( a^{2} - 3a + 9 \right)} =\]

\[= \frac{4a(a^{2} - 3a + 9)}{(a + 3)\left( a^{2} - 3a + 9 \right)} = \frac{4a}{a + 3}\]