Divide and Sum Integrals: Divide x6 by x3 to get x3, and 2x4 by x3 to get 2x. The integral becomes the sum of the integrals of x3, 2x, rac{6x}{x^3+3}, and -rac{9}{x^3+3}.
Integrate x3: Integrate x3 to get 4x4.
Integrate 2x: Integrate 2x to get x2.
Integrate x3+36x: Integrate x3+36x. This is a bit tricky, but notice that the derivative of x3+3 is 3x2, which is close to 6x. Let's use substitution: let u=x3+3, then du=3x2dx. We need to adjust for the 6x, so we multiply du by 32 to get the 6x. The integral of x3+36x becomes x3+36x2 times the integral of x3+36x3.
Integrate 2udu: Integrate 2udu to get 2ln∣u∣.
Substitute u back: Substitute back for u to get 2ln∣x3+3∣.
Integrate −9/(x3+3): Integrate −9/(x3+3). This is a constant over a linear term, so it's just −9 times the integral of 1/(x3+3). This doesn't have an elementary antiderivative, so it looks like I made a mistake here. The integral of −9/(x3+3) should be treated as a separate term.
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