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x*sin(2*x)

Integral of x*sin(2*x) dx

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01xsin(2x)dx\int\limits_{0}^{1} x \sin{\left(2 x \right)}\, dx
Integral(x*sin(2*x), (x, 0, 1))
Detail solution
  1. There are multiple ways to do this integral.

    Method #1

    1. Use integration by parts:

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

      Let u(x)=xu{\left(x \right)} = x and let dv(x)=sin(2x)\operatorname{dv}{\left(x \right)} = \sin{\left(2 x \right)}.

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

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

      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 du2\frac{du}{2}:

          sin(u)4du\int \frac{\sin{\left(u \right)}}{4}\, du

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

            sin(u)2du=sin(u)du2\int \frac{\sin{\left(u \right)}}{2}\, du = \frac{\int \sin{\left(u \right)}\, du}{2}

            1. The integral of sine is negative cosine:

              sin(u)du=cos(u)\int \sin{\left(u \right)}\, du = - \cos{\left(u \right)}

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

          Now substitute uu back in:

          cos(2x)2- \frac{\cos{\left(2 x \right)}}{2}

        Method #2

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

          2sin(x)cos(x)dx=2sin(x)cos(x)dx\int 2 \sin{\left(x \right)} \cos{\left(x \right)}\, dx = 2 \int \sin{\left(x \right)} \cos{\left(x \right)}\, dx

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

            Then let du=sin(x)dxdu = - \sin{\left(x \right)} dx and substitute du- du:

            udu\int u\, du

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

              (u)du=udu\int \left(- u\right)\, du = - \int u\, du

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

                udu=u22\int u\, du = \frac{u^{2}}{2}

              So, the result is: u22- \frac{u^{2}}{2}

            Now substitute uu back in:

            cos2(x)2- \frac{\cos^{2}{\left(x \right)}}{2}

          So, the result is: cos2(x)- \cos^{2}{\left(x \right)}

      Now evaluate the sub-integral.

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

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

      1. Let u=2xu = 2 x.

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

        cos(u)4du\int \frac{\cos{\left(u \right)}}{4}\, du

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

          cos(u)2du=cos(u)du2\int \frac{\cos{\left(u \right)}}{2}\, du = \frac{\int \cos{\left(u \right)}\, du}{2}

          1. The integral of cosine is sine:

            cos(u)du=sin(u)\int \cos{\left(u \right)}\, du = \sin{\left(u \right)}

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

        Now substitute uu back in:

        sin(2x)2\frac{\sin{\left(2 x \right)}}{2}

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

    Method #2

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

      2xsin(x)cos(x)dx=2xsin(x)cos(x)dx\int 2 x \sin{\left(x \right)} \cos{\left(x \right)}\, dx = 2 \int x \sin{\left(x \right)} \cos{\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)=xu{\left(x \right)} = x and let dv(x)=sin(x)cos(x)\operatorname{dv}{\left(x \right)} = \sin{\left(x \right)} \cos{\left(x \right)}.

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

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

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

          Then let du=sin(x)dxdu = - \sin{\left(x \right)} dx and substitute du- du:

          udu\int u\, du

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

            (u)du=udu\int \left(- u\right)\, du = - \int u\, du

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

              udu=u22\int u\, du = \frac{u^{2}}{2}

            So, the result is: u22- \frac{u^{2}}{2}

          Now substitute uu back in:

          cos2(x)2- \frac{\cos^{2}{\left(x \right)}}{2}

        Now evaluate the sub-integral.

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

        (cos2(x)2)dx=cos2(x)dx2\int \left(- \frac{\cos^{2}{\left(x \right)}}{2}\right)\, dx = - \frac{\int \cos^{2}{\left(x \right)}\, dx}{2}

        1. Rewrite the integrand:

          cos2(x)=cos(2x)2+12\cos^{2}{\left(x \right)} = \frac{\cos{\left(2 x \right)}}{2} + \frac{1}{2}

        2. Integrate term-by-term:

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

            cos(2x)2dx=cos(2x)dx2\int \frac{\cos{\left(2 x \right)}}{2}\, dx = \frac{\int \cos{\left(2 x \right)}\, dx}{2}

            1. Let u=2xu = 2 x.

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

              cos(u)4du\int \frac{\cos{\left(u \right)}}{4}\, du

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

                cos(u)2du=cos(u)du2\int \frac{\cos{\left(u \right)}}{2}\, du = \frac{\int \cos{\left(u \right)}\, du}{2}

                1. The integral of cosine is sine:

                  cos(u)du=sin(u)\int \cos{\left(u \right)}\, du = \sin{\left(u \right)}

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

              Now substitute uu back in:

              sin(2x)2\frac{\sin{\left(2 x \right)}}{2}

            So, the result is: sin(2x)4\frac{\sin{\left(2 x \right)}}{4}

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

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

          The result is: x2+sin(2x)4\frac{x}{2} + \frac{\sin{\left(2 x \right)}}{4}

        So, the result is: x4sin(2x)8- \frac{x}{4} - \frac{\sin{\left(2 x \right)}}{8}

      So, the result is: xcos2(x)+x2+sin(2x)4- x \cos^{2}{\left(x \right)} + \frac{x}{2} + \frac{\sin{\left(2 x \right)}}{4}

  2. Add the constant of integration:

    xcos(2x)2+sin(2x)4+constant- \frac{x \cos{\left(2 x \right)}}{2} + \frac{\sin{\left(2 x \right)}}{4}+ \mathrm{constant}


The answer is:

xcos(2x)2+sin(2x)4+constant- \frac{x \cos{\left(2 x \right)}}{2} + \frac{\sin{\left(2 x \right)}}{4}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                         
 |                     sin(2*x)   x*cos(2*x)
 | x*sin(2*x) dx = C + -------- - ----------
 |                        4           2     
/                                           
sin(2x)2xcos(2x)4{{\sin \left(2\,x\right)-2\,x\,\cos \left(2\,x\right)}\over{4}}
The graph
0.001.000.100.200.300.400.500.600.700.800.900.01.0
The answer [src]
  cos(2)   sin(2)
- ------ + ------
    2        4   
sin22cos24{{\sin 2-2\,\cos 2}\over{4}}
=
=
  cos(2)   sin(2)
- ------ + ------
    2        4   
cos(2)2+sin(2)4- \frac{\cos{\left(2 \right)}}{2} + \frac{\sin{\left(2 \right)}}{4}
Numerical answer [src]
0.435397774979992
0.435397774979992
The graph
Integral of x*sin(2*x) dx

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