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x*cos(x/2)

Integral of x*cos(x/2) dx

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The solution

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01xcos(x2)dx\int\limits_{0}^{1} x \cos{\left(\frac{x}{2} \right)}\, dx
Integral(x*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)=xu{\left(x \right)} = x and let dv(x)=cos(x2)\operatorname{dv}{\left(x \right)} = \cos{\left(\frac{x}{2} \right)}.

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

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

    1. Let u=x2u = \frac{x}{2}.

      Then let du=dx2du = \frac{dx}{2} and substitute 2du2 du:

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

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

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

        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: 2sin(u)2 \sin{\left(u \right)}

      Now substitute uu back in:

      2sin(x2)2 \sin{\left(\frac{x}{2} \right)}

    Now evaluate the sub-integral.

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

    2sin(x2)dx=2sin(x2)dx\int 2 \sin{\left(\frac{x}{2} \right)}\, dx = 2 \int \sin{\left(\frac{x}{2} \right)}\, dx

    1. Let u=x2u = \frac{x}{2}.

      Then let du=dx2du = \frac{dx}{2} and substitute 2du2 du:

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

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

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

        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: 2cos(u)- 2 \cos{\left(u \right)}

      Now substitute uu back in:

      2cos(x2)- 2 \cos{\left(\frac{x}{2} \right)}

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

  3. Add the constant of integration:

    2xsin(x2)+4cos(x2)+constant2 x \sin{\left(\frac{x}{2} \right)} + 4 \cos{\left(\frac{x}{2} \right)}+ \mathrm{constant}


The answer is:

2xsin(x2)+4cos(x2)+constant2 x \sin{\left(\frac{x}{2} \right)} + 4 \cos{\left(\frac{x}{2} \right)}+ \mathrm{constant}

The answer (Indefinite) [src]
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xcos(x2)dx=C+2xsin(x2)+4cos(x2)\int x \cos{\left(\frac{x}{2} \right)}\, dx = C + 2 x \sin{\left(\frac{x}{2} \right)} + 4 \cos{\left(\frac{x}{2} \right)}
The graph
0.001.000.100.200.300.400.500.600.700.800.9005
The answer [src]
-4 + 2*sin(1/2) + 4*cos(1/2)
4+2sin(12)+4cos(12)-4 + 2 \sin{\left(\frac{1}{2} \right)} + 4 \cos{\left(\frac{1}{2} \right)}
=
=
-4 + 2*sin(1/2) + 4*cos(1/2)
4+2sin(12)+4cos(12)-4 + 2 \sin{\left(\frac{1}{2} \right)} + 4 \cos{\left(\frac{1}{2} \right)}
-4 + 2*sin(1/2) + 4*cos(1/2)
Numerical answer [src]
0.469181324769897
0.469181324769897
The graph
Integral of x*cos(x/2) dx

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