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Integral of (2*x+3)/(2*x+1) dx

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The solution

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  1           
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 |  2*x + 3   
 |  ------- dx
 |  2*x + 1   
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012x+32x+1dx\int\limits_{0}^{1} \frac{2 x + 3}{2 x + 1}\, dx
Integral((2*x + 3)/(2*x + 1), (x, 0, 1))
Detail solution
  1. There are multiple ways to do this integral.

    Method #1

    1. Let u=2xu = 2 x.

      Then let du=2dxdu = 2 dx and substitute dudu:

      u+32u+2du\int \frac{u + 3}{2 u + 2}\, du

      1. Rewrite the integrand:

        u+32u+2=12+1u+1\frac{u + 3}{2 u + 2} = \frac{1}{2} + \frac{1}{u + 1}

      2. Integrate term-by-term:

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

          12du=u2\int \frac{1}{2}\, du = \frac{u}{2}

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

          Then let du=dudu = du 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(u+1)\log{\left(u + 1 \right)}

        The result is: u2+log(u+1)\frac{u}{2} + \log{\left(u + 1 \right)}

      Now substitute uu back in:

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

    Method #2

    1. Rewrite the integrand:

      2x+32x+1=1+22x+1\frac{2 x + 3}{2 x + 1} = 1 + \frac{2}{2 x + 1}

    2. Integrate term-by-term:

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

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

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

        22x+1dx=212x+1dx\int \frac{2}{2 x + 1}\, dx = 2 \int \frac{1}{2 x + 1}\, dx

        1. Let u=2x+1u = 2 x + 1.

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

          12udu\int \frac{1}{2 u}\, du

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

            1udu=1udu2\int \frac{1}{u}\, du = \frac{\int \frac{1}{u}\, du}{2}

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

            So, the result is: log(u)2\frac{\log{\left(u \right)}}{2}

          Now substitute uu back in:

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

        So, the result is: log(2x+1)\log{\left(2 x + 1 \right)}

      The result is: x+log(2x+1)x + \log{\left(2 x + 1 \right)}

    Method #3

    1. Rewrite the integrand:

      2x+32x+1=2x2x+1+32x+1\frac{2 x + 3}{2 x + 1} = \frac{2 x}{2 x + 1} + \frac{3}{2 x + 1}

    2. Integrate term-by-term:

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

        2x2x+1dx=2x2x+1dx\int \frac{2 x}{2 x + 1}\, dx = 2 \int \frac{x}{2 x + 1}\, dx

        1. Rewrite the integrand:

          x2x+1=1212(2x+1)\frac{x}{2 x + 1} = \frac{1}{2} - \frac{1}{2 \left(2 x + 1\right)}

        2. Integrate term-by-term:

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

            12dx=x2\int \frac{1}{2}\, dx = \frac{x}{2}

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

            (12(2x+1))dx=12x+1dx2\int \left(- \frac{1}{2 \left(2 x + 1\right)}\right)\, dx = - \frac{\int \frac{1}{2 x + 1}\, dx}{2}

            1. Let u=2x+1u = 2 x + 1.

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

              12udu\int \frac{1}{2 u}\, du

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

                1udu=1udu2\int \frac{1}{u}\, du = \frac{\int \frac{1}{u}\, du}{2}

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

                So, the result is: log(u)2\frac{\log{\left(u \right)}}{2}

              Now substitute uu back in:

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

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

          The result is: x2log(2x+1)4\frac{x}{2} - \frac{\log{\left(2 x + 1 \right)}}{4}

        So, the result is: xlog(2x+1)2x - \frac{\log{\left(2 x + 1 \right)}}{2}

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

        32x+1dx=312x+1dx\int \frac{3}{2 x + 1}\, dx = 3 \int \frac{1}{2 x + 1}\, dx

        1. Let u=2x+1u = 2 x + 1.

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

          12udu\int \frac{1}{2 u}\, du

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

            1udu=1udu2\int \frac{1}{u}\, du = \frac{\int \frac{1}{u}\, du}{2}

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

            So, the result is: log(u)2\frac{\log{\left(u \right)}}{2}

          Now substitute uu back in:

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

        So, the result is: 3log(2x+1)2\frac{3 \log{\left(2 x + 1 \right)}}{2}

      The result is: xlog(2x+1)2+3log(2x+1)2x - \frac{\log{\left(2 x + 1 \right)}}{2} + \frac{3 \log{\left(2 x + 1 \right)}}{2}

  2. Add the constant of integration:

    x+log(2x+1)+constantx + \log{\left(2 x + 1 \right)}+ \mathrm{constant}


The answer is:

x+log(2x+1)+constantx + \log{\left(2 x + 1 \right)}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                 
 |                                  
 | 2*x + 3                          
 | ------- dx = C + x + log(1 + 2*x)
 | 2*x + 1                          
 |                                  
/                                   
2x+32x+1dx=C+x+log(2x+1)\int \frac{2 x + 3}{2 x + 1}\, dx = C + x + \log{\left(2 x + 1 \right)}
The graph
0.001.000.100.200.300.400.500.600.700.800.9005
The answer [src]
1 + log(3)
1+log(3)1 + \log{\left(3 \right)}
=
=
1 + log(3)
1+log(3)1 + \log{\left(3 \right)}
1 + log(3)
Numerical answer [src]
2.09861228866811
2.09861228866811

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