Trigonometric Substitution: Step 1: Use trigonometric substitution because the integrand has the form (a2+x2)2n. Let x=3tan(θ), then dx=3sec2(θ)dθ.
Substitute and Simplify: Step 2: Substitute x=3tan(θ) into the integral. The integral becomes ∫(9+(3tan(θ))2)233sec2(θ)dθ. Simplify the denominator: 9+9tan2(θ)=9sec2(θ).
Integral Simplification: Step 3: The integral simplifies to \int\frac{\(3\)\sec^\(2\)(\theta)d\theta}{\(9\)\sec^\(3\)(\theta)} = \int\frac{\(3\)\sec^\(2\)(\theta)d\theta}{\(9\)\sec^\(3\)(\theta)} = \int\left(\frac{\(1\)}{\(3\)}\right)\sec^{\(-1\)}(\theta)d\theta = \left(\frac{\(1\)}{\(3\)}\right)\int\cos(\theta)d\theta.
Integrate Cosine: Step \(4: Integrate (31)cos(θ)dθ. The integral of cos(θ) is sin(θ), so the integral becomes (31)sin(θ)+C.
Substitute Back for Theta: Step 5: Substitute back for θ using x=3tan(θ). We have tan(θ)=3x, so θ=arctan(3x). Therefore, sin(θ)=sin(arctan(3x)).
Use Trigonometric Identity: Step 6: Use the identity sin(arctan(u))=1+u2u to find sin(arctan(3x))=1+(3x)23x=9+x2x.
Final Answer: Step 7: The final answer for the indefinite integral is (31)(9+x2x)+C.
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