Mister Exam

Integral of 13xarctgxdx dx

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The solution

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0113xatan(x)1dx\int\limits_{0}^{1} 13 x \operatorname{atan}{\left(x \right)} 1\, dx
Integral(13*x*atan(x)*1, (x, 0, 1))
Detail solution
  1. The integral of a constant times a function is the constant times the integral of the function:

    13xatan(x)1dx=13xatan(x)dx\int 13 x \operatorname{atan}{\left(x \right)} 1\, dx = 13 \int x \operatorname{atan}{\left(x \right)}\, dx

    1. Use integration by parts:

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

      Let u(x)=atan(x)u{\left(x \right)} = \operatorname{atan}{\left(x \right)} and let dv(x)=x\operatorname{dv}{\left(x \right)} = x.

      Then du(x)=1x2+1\operatorname{du}{\left(x \right)} = \frac{1}{x^{2} + 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(x2+1)dx=x2x2+1dx2\int \frac{x^{2}}{2 \left(x^{2} + 1\right)}\, dx = \frac{\int \frac{x^{2}}{x^{2} + 1}\, dx}{2}

      1. Rewrite the integrand:

        x2x2+1=11x2+1\frac{x^{2}}{x^{2} + 1} = 1 - \frac{1}{x^{2} + 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:

          (1x2+1)dx=1x2+1dx\int \left(- \frac{1}{x^{2} + 1}\right)\, dx = - \int \frac{1}{x^{2} + 1}\, dx

          1. The integral of 1x2+1\frac{1}{x^{2} + 1} is atan(x)\operatorname{atan}{\left(x \right)}.

          So, the result is: atan(x)- \operatorname{atan}{\left(x \right)}

        The result is: xatan(x)x - \operatorname{atan}{\left(x \right)}

      So, the result is: x2atan(x)2\frac{x}{2} - \frac{\operatorname{atan}{\left(x \right)}}{2}

    So, the result is: 13x2atan(x)213x2+13atan(x)2\frac{13 x^{2} \operatorname{atan}{\left(x \right)}}{2} - \frac{13 x}{2} + \frac{13 \operatorname{atan}{\left(x \right)}}{2}

  2. Add the constant of integration:

    13x2atan(x)213x2+13atan(x)2+constant\frac{13 x^{2} \operatorname{atan}{\left(x \right)}}{2} - \frac{13 x}{2} + \frac{13 \operatorname{atan}{\left(x \right)}}{2}+ \mathrm{constant}


The answer is:

13x2atan(x)213x2+13atan(x)2+constant\frac{13 x^{2} \operatorname{atan}{\left(x \right)}}{2} - \frac{13 x}{2} + \frac{13 \operatorname{atan}{\left(x \right)}}{2}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                                2        
 |                         13*x   13*atan(x)   13*x *atan(x)
 | 13*x*atan(x)*1 dx = C - ---- + ---------- + -------------
 |                          2         2              2      
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13xatan(x)1dx=C+13x2atan(x)213x2+13atan(x)2\int 13 x \operatorname{atan}{\left(x \right)} 1\, dx = C + \frac{13 x^{2} \operatorname{atan}{\left(x \right)}}{2} - \frac{13 x}{2} + \frac{13 \operatorname{atan}{\left(x \right)}}{2}
The graph
0.001.000.100.200.300.400.500.600.700.800.90020
The answer [src]
  13   13*pi
- -- + -----
  2      4  
132+13π4- \frac{13}{2} + \frac{13 \pi}{4}
=
=
  13   13*pi
- -- + -----
  2      4  
132+13π4- \frac{13}{2} + \frac{13 \pi}{4}
Numerical answer [src]
3.71017612416683
3.71017612416683
The graph
Integral of 13xarctgxdx dx

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