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Evaluate the integral of e^(1/x) / x^2 from [1,2].

I let u =1/x, but then I am stuck because I am not sure what is the derivative of 1/x is?

The answer in the book is e- sqrt(e)

  • Math -

    let u=1/x
    du = -1/x^2 dx

    ∫e^(1/x)/x^2 dx
    = -∫e^u du
    = -e^u = -e^(1/x) [1,2]
    = -e^(1/2) + e^(1/1)

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