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Integral of log(1+x)/sqrt(1+x) dx

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  3              
  /              
 |               
 |  log(1 + x)   
 |  ---------- dx
 |    _______    
 |  \/ 1 + x     
 |               
/                
0                
03log(x+1)x+1dx\int\limits_{0}^{3} \frac{\log{\left(x + 1 \right)}}{\sqrt{x + 1}}\, dx
Integral(log(1 + x)/sqrt(1 + x), (x, 0, 3))
Detail solution
  1. There are multiple ways to do this integral.

    Method #1

    1. Let u=log(x+1)u = \log{\left(x + 1 \right)}.

      Then let du=dxx+1du = \frac{dx}{x + 1} and substitute dudu:

      ueu2du\int u e^{\frac{u}{2}}\, du

      1. Use integration by parts:

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

        Let u(u)=uu{\left(u \right)} = u and let dv(u)=eu2\operatorname{dv}{\left(u \right)} = e^{\frac{u}{2}}.

        Then du(u)=1\operatorname{du}{\left(u \right)} = 1.

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

        1. Let u=u2u = \frac{u}{2}.

          Then let du=du2du = \frac{du}{2} and substitute 2du2 du:

          2eudu\int 2 e^{u}\, du

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

            False\text{False}

            1. The integral of the exponential function is itself.

              eudu=eu\int e^{u}\, du = e^{u}

            So, the result is: 2eu2 e^{u}

          Now substitute uu back in:

          2eu22 e^{\frac{u}{2}}

        Now evaluate the sub-integral.

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

        2eu2du=2eu2du\int 2 e^{\frac{u}{2}}\, du = 2 \int e^{\frac{u}{2}}\, du

        1. Let u=u2u = \frac{u}{2}.

          Then let du=du2du = \frac{du}{2} and substitute 2du2 du:

          2eudu\int 2 e^{u}\, du

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

            False\text{False}

            1. The integral of the exponential function is itself.

              eudu=eu\int e^{u}\, du = e^{u}

            So, the result is: 2eu2 e^{u}

          Now substitute uu back in:

          2eu22 e^{\frac{u}{2}}

        So, the result is: 4eu24 e^{\frac{u}{2}}

      Now substitute uu back in:

      2x+1log(x+1)4x+12 \sqrt{x + 1} \log{\left(x + 1 \right)} - 4 \sqrt{x + 1}

    Method #2

    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(x+1)u{\left(x \right)} = \log{\left(x + 1 \right)} and let dv(x)=1x+1\operatorname{dv}{\left(x \right)} = \frac{1}{\sqrt{x + 1}}.

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

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

      1. Let u=x+1u = x + 1.

        Then let du=dxdu = dx and substitute dudu:

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

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          1udu=2u\int \frac{1}{\sqrt{u}}\, du = 2 \sqrt{u}

        Now substitute uu back in:

        2x+12 \sqrt{x + 1}

      Now evaluate the sub-integral.

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

      2x+1dx=21x+1dx\int \frac{2}{\sqrt{x + 1}}\, dx = 2 \int \frac{1}{\sqrt{x + 1}}\, dx

      1. Let u=x+1u = x + 1.

        Then let du=dxdu = dx and substitute dudu:

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

        1. The integral of unu^{n} is un+1n+1\frac{u^{n + 1}}{n + 1} when n1n \neq -1:

          1udu=2u\int \frac{1}{\sqrt{u}}\, du = 2 \sqrt{u}

        Now substitute uu back in:

        2x+12 \sqrt{x + 1}

      So, the result is: 4x+14 \sqrt{x + 1}

  2. Now simplify:

    2x+1(log(x+1)2)2 \sqrt{x + 1} \left(\log{\left(x + 1 \right)} - 2\right)

  3. Add the constant of integration:

    2x+1(log(x+1)2)+constant2 \sqrt{x + 1} \left(\log{\left(x + 1 \right)} - 2\right)+ \mathrm{constant}


The answer is:

2x+1(log(x+1)2)+constant2 \sqrt{x + 1} \left(\log{\left(x + 1 \right)} - 2\right)+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                                        
 |                                                         
 | log(1 + x)              _______       _______           
 | ---------- dx = C - 4*\/ 1 + x  + 2*\/ 1 + x *log(1 + x)
 |   _______                                               
 | \/ 1 + x                                                
 |                                                         
/                                                          
log(x+1)x+1dx=C+2x+1log(x+1)4x+1\int \frac{\log{\left(x + 1 \right)}}{\sqrt{x + 1}}\, dx = C + 2 \sqrt{x + 1} \log{\left(x + 1 \right)} - 4 \sqrt{x + 1}
The graph
0.003.000.250.500.751.001.251.501.752.002.252.502.755-5
The answer [src]
-4 + 4*log(4)
4+4log(4)-4 + 4 \log{\left(4 \right)}
=
=
-4 + 4*log(4)
4+4log(4)-4 + 4 \log{\left(4 \right)}
-4 + 4*log(4)
Numerical answer [src]
1.54517744447956
1.54517744447956

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