Sr Examen

Integral de ln|1-x| dx

Límites de integración:

interior superior
v

Gráfico:

interior superior

Definida a trozos:

Solución

Ha introducido [src]
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02log(1x)dx\int\limits_{0}^{2} \log{\left(\left|{1 - x}\right| \right)}\, dx
Integral(log(|1 - x|), (x, 0, 2))
Solución detallada
  1. Usamos la integración por partes:

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

    que u(x)=log(1x)u{\left(x \right)} = \log{\left(\left|{1 - x}\right| \right)} y que dv(x)=1\operatorname{dv}{\left(x \right)} = 1.

    Entonces du(x)=((1re(x))ddxre(x)+im(x)ddxim(x))sign(x1)(x1)1x\operatorname{du}{\left(x \right)} = \frac{\left(- \left(1 - \operatorname{re}{\left(x\right)}\right) \frac{d}{d x} \operatorname{re}{\left(x\right)} + \operatorname{im}{\left(x\right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}\right) \operatorname{sign}{\left(x - 1 \right)}}{\left(x - 1\right) \left|{1 - x}\right|}.

    Para buscar v(x)v{\left(x \right)}:

    1. La integral de las constantes tienen esta constante multiplicada por la variable de integración:

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

    Ahora resolvemos podintegral.

  2. Hay varias maneras de calcular esta integral.

    Método #1

    1. Vuelva a escribir el integrando:

      x((1re(x))ddxre(x)+im(x)ddxim(x))sign(x1)(x1)1x=xre(x)sign(x1)ddxre(x)+xim(x)sign(x1)ddxim(x)xsign(x1)ddxre(x)x1x1x\frac{x \left(- \left(1 - \operatorname{re}{\left(x\right)}\right) \frac{d}{d x} \operatorname{re}{\left(x\right)} + \operatorname{im}{\left(x\right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}\right) \operatorname{sign}{\left(x - 1 \right)}}{\left(x - 1\right) \left|{1 - x}\right|} = \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)} + x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)} - x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}

    2. Vuelva a escribir el integrando:

      xre(x)sign(x1)ddxre(x)+xim(x)sign(x1)ddxim(x)xsign(x1)ddxre(x)x1x1x=xre(x)sign(x1)ddxre(x)x1x1x+xim(x)sign(x1)ddxim(x)x1x1xxsign(x1)ddxre(x)x1x1x\frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)} + x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)} - x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|} = \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|} + \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|} - \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}

    3. Integramos término a término:

      1. No puedo encontrar los pasos en la búsqueda de esta integral.

        Pero la integral

        xre(x)sign(x1)ddxre(x)(x1)1xdx\int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

      1. No puedo encontrar los pasos en la búsqueda de esta integral.

        Pero la integral

        xim(x)sign(x1)ddxim(x)(x1)1xdx\int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

      1. La integral del producto de una función por una constante es la constante por la integral de esta función:

        (xsign(x1)ddxre(x)x1x1x)dx=xsign(x1)ddxre(x)x1x1xdx\int \left(- \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}\right)\, dx = - \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}\, dx

        1. No puedo encontrar los pasos en la búsqueda de esta integral.

          Pero la integral

          xsign(x1)ddxre(x)(x1)1xdx\int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

        Por lo tanto, el resultado es: xsign(x1)ddxre(x)(x1)1xdx- \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

      El resultado es: xsign(x1)ddxre(x)(x1)1xdx+xre(x)sign(x1)ddxre(x)(x1)1xdx+xim(x)sign(x1)ddxim(x)(x1)1xdx- \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx + \int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx + \int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

    Método #2

    1. Vuelva a escribir el integrando:

      x((1re(x))ddxre(x)+im(x)ddxim(x))sign(x1)(x1)1x=xre(x)sign(x1)ddxre(x)x1x1x+xim(x)sign(x1)ddxim(x)x1x1xxsign(x1)ddxre(x)x1x1x\frac{x \left(- \left(1 - \operatorname{re}{\left(x\right)}\right) \frac{d}{d x} \operatorname{re}{\left(x\right)} + \operatorname{im}{\left(x\right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}\right) \operatorname{sign}{\left(x - 1 \right)}}{\left(x - 1\right) \left|{1 - x}\right|} = \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|} + \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|} - \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}

    2. Integramos término a término:

      1. No puedo encontrar los pasos en la búsqueda de esta integral.

        Pero la integral

        xre(x)sign(x1)ddxre(x)(x1)1xdx\int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

      1. No puedo encontrar los pasos en la búsqueda de esta integral.

        Pero la integral

        xim(x)sign(x1)ddxim(x)(x1)1xdx\int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

      1. La integral del producto de una función por una constante es la constante por la integral de esta función:

        (xsign(x1)ddxre(x)x1x1x)dx=xsign(x1)ddxre(x)x1x1xdx\int \left(- \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}\right)\, dx = - \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{x \left|{1 - x}\right| - \left|{1 - x}\right|}\, dx

        1. No puedo encontrar los pasos en la búsqueda de esta integral.

          Pero la integral

          xsign(x1)ddxre(x)(x1)1xdx\int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

        Por lo tanto, el resultado es: xsign(x1)ddxre(x)(x1)1xdx- \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

      El resultado es: xsign(x1)ddxre(x)(x1)1xdx+xre(x)sign(x1)ddxre(x)(x1)1xdx+xim(x)sign(x1)ddxim(x)(x1)1xdx- \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx + \int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx + \int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx

  3. Ahora simplificar:

    xlog(x1)+xsign(x1)ddxre(x)(x1)x1dxxre(x)sign(x1)ddxre(x)(x1)x1dxxim(x)sign(x1)ddxim(x)(x1)x1dxx \log{\left(\left|{x - 1}\right| \right)} + \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx - \int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx - \int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx

  4. Añadimos la constante de integración:

    xlog(x1)+xsign(x1)ddxre(x)(x1)x1dxxre(x)sign(x1)ddxre(x)(x1)x1dxxim(x)sign(x1)ddxim(x)(x1)x1dx+constantx \log{\left(\left|{x - 1}\right| \right)} + \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx - \int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx - \int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx+ \mathrm{constant}


Respuesta:

xlog(x1)+xsign(x1)ddxre(x)(x1)x1dxxre(x)sign(x1)ddxre(x)(x1)x1dxxim(x)sign(x1)ddxim(x)(x1)x1dx+constantx \log{\left(\left|{x - 1}\right| \right)} + \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx - \int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx - \int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{x - 1}\right|}\, dx+ \mathrm{constant}

Respuesta (Indefinida) [src]
                           /                                      /                                                       /                           
                          |                                      |                                                       |                            
                          |   d                                  |   d                                                   |   d                        
  /                       | x*--(im(x))*im(x)*sign(-1 + x)       | x*--(re(x))*re(x)*sign(-1 + x)                        | x*--(re(x))*sign(-1 + x)   
 |                        |   dx                                 |   dx                                                  |   dx                       
 | log(|1 - x|) dx = C -  | ------------------------------ dx -  | ------------------------------ dx + x*log(|1 - x|) +  | ------------------------ dx
 |                        |        (-1 + x)*|1 - x|              |        (-1 + x)*|1 - x|                               |     (-1 + x)*|1 - x|       
/                         |                                      |                                                       |                            
                         /                                      /                                                       /                             
log(1x)dx=C+xlog(1x)+xsign(x1)ddxre(x)(x1)1xdxxre(x)sign(x1)ddxre(x)(x1)1xdxxim(x)sign(x1)ddxim(x)(x1)1xdx\int \log{\left(\left|{1 - x}\right| \right)}\, dx = C + x \log{\left(\left|{1 - x}\right| \right)} + \int \frac{x \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx - \int \frac{x \operatorname{re}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{re}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx - \int \frac{x \operatorname{im}{\left(x\right)} \operatorname{sign}{\left(x - 1 \right)} \frac{d}{d x} \operatorname{im}{\left(x\right)}}{\left(x - 1\right) \left|{1 - x}\right|}\, dx
Gráfica
0.02.00.20.40.60.81.01.21.41.61.85-10
Respuesta [src]
-2
2-2
=
=
-2
2-2
-2
Respuesta numérica [src]
-inf
-inf

    Estos ejemplos se pueden aplicar para introducción de los límites de integración inferior y superior.