Mister Exam

Integral of xln(x-1)dx dx

Limits of integration:

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The solution

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01xlog(x1)1dx\int\limits_{0}^{1} x \log{\left(x - 1 \right)} 1\, dx
Integral(x*log(x - 1*1)*1, (x, 0, 1))
Detail solution
  1. Use integration by parts:

    udv=uvvdu\int \operatorname{u} \operatorname{dv} = \operatorname{u}\operatorname{v} - \int \operatorname{v} \operatorname{du}

    Let u(x)=log(x1)u{\left(x \right)} = \log{\left(x - 1 \right)} and let dv(x)=x\operatorname{dv}{\left(x \right)} = x.

    Then du(x)=1x1\operatorname{du}{\left(x \right)} = \frac{1}{x - 1}.

    To find v(x)v{\left(x \right)}:

    1. The integral of xnx^{n} is xn+1n+1\frac{x^{n + 1}}{n + 1} when n1n \neq -1:

      xdx=x22\int x\, dx = \frac{x^{2}}{2}

    Now evaluate the sub-integral.

  2. The integral of a constant times a function is the constant times the integral of the function:

    x22(x1)dx=x2x1dx2\int \frac{x^{2}}{2 \left(x - 1\right)}\, dx = \frac{\int \frac{x^{2}}{x - 1}\, dx}{2}

    1. Rewrite the integrand:

      x2x1=x+1+1x1\frac{x^{2}}{x - 1} = x + 1 + \frac{1}{x - 1}

    2. Integrate term-by-term:

      1. The integral of xnx^{n} is xn+1n+1\frac{x^{n + 1}}{n + 1} when n1n \neq -1:

        xdx=x22\int x\, dx = \frac{x^{2}}{2}

      1. The integral of a constant is the constant times the variable of integration:

        1dx=x\int 1\, dx = x

      1. Let u=x1u = x - 1.

        Then let du=dxdu = dx and substitute dudu:

        1udu\int \frac{1}{u}\, du

        1. The integral of 1u\frac{1}{u} is log(u)\log{\left(u \right)}.

        Now substitute uu back in:

        log(x1)\log{\left(x - 1 \right)}

      The result is: x22+x+log(x1)\frac{x^{2}}{2} + x + \log{\left(x - 1 \right)}

    So, the result is: x24+x2+log(x1)2\frac{x^{2}}{4} + \frac{x}{2} + \frac{\log{\left(x - 1 \right)}}{2}

  3. Now simplify:

    x2log(x1)2x24x2log(x1)2\frac{x^{2} \log{\left(x - 1 \right)}}{2} - \frac{x^{2}}{4} - \frac{x}{2} - \frac{\log{\left(x - 1 \right)}}{2}

  4. Add the constant of integration:

    x2log(x1)2x24x2log(x1)2+constant\frac{x^{2} \log{\left(x - 1 \right)}}{2} - \frac{x^{2}}{4} - \frac{x}{2} - \frac{\log{\left(x - 1 \right)}}{2}+ \mathrm{constant}


The answer is:

x2log(x1)2x24x2log(x1)2+constant\frac{x^{2} \log{\left(x - 1 \right)}}{2} - \frac{x^{2}}{4} - \frac{x}{2} - \frac{\log{\left(x - 1 \right)}}{2}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                           2    2           
 |                         x   log(-1 + x)   x    x *log(x - 1)
 | x*log(x - 1)*1 dx = C - - - ----------- - -- + -------------
 |                         2        2        4          2      
/                                                              
log(x1)x22x2+2x2+log(x1)2{{\log \left(x-1\right)\,x^2}\over{2}}-{{{{x^2+2\,x}\over{2}}+\log \left(x-1\right)}\over{2}}
The answer [src]
  3   pi*I
- - + ----
  4    2  
2log(1)34{{2\,\log \left(-1\right)-3}\over{4}}
=
=
  3   pi*I
- - + ----
  4    2  
34+iπ2- \frac{3}{4} + \frac{i \pi}{2}
Numerical answer [src]
(-0.75 + 1.5707963267949j)
(-0.75 + 1.5707963267949j)

    Use the examples entering the upper and lower limits of integration.