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x^2cos^2x

Integral of x^2cos^2x dx

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01x2cos2(x)dx\int\limits_{0}^{1} x^{2} \cos^{2}{\left(x \right)}\, dx
Integral(x^2*cos(x)^2, (x, 0, 1))
Detail solution
  1. Use integration by parts:

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

    Let u(x)=x2u{\left(x \right)} = x^{2} and let dv(x)=cos2(x)\operatorname{dv}{\left(x \right)} = \cos^{2}{\left(x \right)}.

    Then du(x)=2x\operatorname{du}{\left(x \right)} = 2 x.

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

    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}

    Now evaluate the sub-integral.

  2. Use integration by parts:

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

    Let u(x)=x2u{\left(x \right)} = \frac{x}{2} and let dv(x)=2x+sin(2x)\operatorname{dv}{\left(x \right)} = 2 x + \sin{\left(2 x \right)}.

    Then du(x)=12\operatorname{du}{\left(x \right)} = \frac{1}{2}.

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

    1. Integrate term-by-term:

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

        2xdx=2xdx\int 2 x\, dx = 2 \int x\, dx

        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}

        So, the result is: x2x^{2}

      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. There are multiple ways to do this integral.

            Method #1

            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}

            Method #2

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

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

              udu\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}

              Now substitute uu back in:

              sin2(x)2\frac{\sin^{2}{\left(x \right)}}{2}

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

      The result is: x2cos(2x)2x^{2} - \frac{\cos{\left(2 x \right)}}{2}

    Now evaluate the sub-integral.

  3. Integrate term-by-term:

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

      x22dx=x2dx2\int \frac{x^{2}}{2}\, dx = \frac{\int x^{2}\, dx}{2}

      1. The integral of xnx^{n} is xn+1n+1\frac{x^{n + 1}}{n + 1} when n1n \neq -1:

        x2dx=x33\int x^{2}\, dx = \frac{x^{3}}{3}

      So, the result is: x36\frac{x^{3}}{6}

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

      (cos(2x)4)dx=cos(2x)dx4\int \left(- \frac{\cos{\left(2 x \right)}}{4}\right)\, dx = - \frac{\int \cos{\left(2 x \right)}\, dx}{4}

      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)8- \frac{\sin{\left(2 x \right)}}{8}

    The result is: x36sin(2x)8\frac{x^{3}}{6} - \frac{\sin{\left(2 x \right)}}{8}

  4. Now simplify:

    x36+x2sin(2x)4+xcos(2x)4sin(2x)8\frac{x^{3}}{6} + \frac{x^{2} \sin{\left(2 x \right)}}{4} + \frac{x \cos{\left(2 x \right)}}{4} - \frac{\sin{\left(2 x \right)}}{8}

  5. Add the constant of integration:

    x36+x2sin(2x)4+xcos(2x)4sin(2x)8+constant\frac{x^{3}}{6} + \frac{x^{2} \sin{\left(2 x \right)}}{4} + \frac{x \cos{\left(2 x \right)}}{4} - \frac{\sin{\left(2 x \right)}}{8}+ \mathrm{constant}


The answer is:

x36+x2sin(2x)4+xcos(2x)4sin(2x)8+constant\frac{x^{3}}{6} + \frac{x^{2} \sin{\left(2 x \right)}}{4} + \frac{x \cos{\left(2 x \right)}}{4} - \frac{\sin{\left(2 x \right)}}{8}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                                          / 2   cos(2*x)\
 |                                 3                       x*|x  - --------|
 |  2    2             sin(2*x)   x     2 /x   sin(2*x)\     \        2    /
 | x *cos (x) dx = C - -------- + -- + x *|- + --------| - -----------------
 |                        8       6       \2      4    /           2        
/                                                                           
(6x23)sin(2x)+6xcos(2x)+4x324{{\left(6\,x^2-3\right)\,\sin \left(2\,x\right)+6\,x\,\cos \left(2 \,x\right)+4\,x^3}\over{24}}
The graph
0.001.000.100.200.300.400.500.600.700.800.900.00.5
The answer [src]
     2           2                   
  sin (1)   5*cos (1)   cos(1)*sin(1)
- ------- + --------- + -------------
     12         12            4      
3sin2+6cos2+424{{3\,\sin 2+6\,\cos 2+4}\over{24}}
=
=
     2           2                   
  sin (1)   5*cos (1)   cos(1)*sin(1)
- ------- + --------- + -------------
     12         12            4      
sin2(1)12+sin(1)cos(1)4+5cos2(1)12- \frac{\sin^{2}{\left(1 \right)}}{12} + \frac{\sin{\left(1 \right)} \cos{\left(1 \right)}}{4} + \frac{5 \cos^{2}{\left(1 \right)}}{12}
Numerical answer [src]
0.176292135883091
0.176292135883091
The graph
Integral of x^2cos^2x dx

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