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CalculusHardNon-Elementary Integration

Non-Elementary Integration · Hard problem

Glasser's master theorem gives ∫−∞∞f ⁣(x−1x)dx=∫−∞∞f(x) dx\displaystyle\int_{-\infty}^{\infty}f\!\left(x-\dfrac1x\right)dx=\int_{-\infty}^{\infty}f(x)\,dx for integrable ff. Evaluate ∫−∞∞e−(x2+1/x2) dx\displaystyle\int_{-\infty}^{\infty}e^{-\left(x^2+1/x^2\right)}\,dx.