How do you integrate $9^{\sin x}$

calculusintegration

I understand how you would differentiate it, but how would you integrate it?
After plugging it into integral calculator, it says that it is non-elemetary, what does this mean too?

Best Answer

It does not have any closed-form. What we know is $$\int _{x=0}^{2\pi} 9^{\sin(x)} \mathrm{d} x=\int _{x=0}^{2\pi} e^{\ln(9)\sin(x)} \mathrm{d} x=\mathrm{I}_0(\ln(9)),$$ where $\mathrm{I}_0(\cdot)$ is the modified Bessel function of the first kind.

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