Mister Exam

Integral of tg(4x-2) dx

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The solution

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13tan(4x2)dx\int\limits_{1}^{3} \tan{\left(4 x - 2 \right)}\, dx
Integral(tan(4*x - 2), (x, 1, 3))
Detail solution
  1. Rewrite the integrand:

    tan(4x2)=sin(4x2)cos(4x2)\tan{\left(4 x - 2 \right)} = \frac{\sin{\left(4 x - 2 \right)}}{\cos{\left(4 x - 2 \right)}}

  2. There are multiple ways to do this integral.

    Method #1

    1. Let u=cos(4x2)u = \cos{\left(4 x - 2 \right)}.

      Then let du=4sin(4x2)dxdu = - 4 \sin{\left(4 x - 2 \right)} dx and substitute du4- \frac{du}{4}:

      (14u)du\int \left(- \frac{1}{4 u}\right)\, du

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

        1udu=1udu4\int \frac{1}{u}\, du = - \frac{\int \frac{1}{u}\, du}{4}

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

        So, the result is: log(u)4- \frac{\log{\left(u \right)}}{4}

      Now substitute uu back in:

      log(cos(4x2))4- \frac{\log{\left(\cos{\left(4 x - 2 \right)} \right)}}{4}

    Method #2

    1. Let u=4x2u = 4 x - 2.

      Then let du=4dxdu = 4 dx and substitute du4\frac{du}{4}:

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

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

        sin(u)cos(u)du=sin(u)cos(u)du4\int \frac{\sin{\left(u \right)}}{\cos{\left(u \right)}}\, du = \frac{\int \frac{\sin{\left(u \right)}}{\cos{\left(u \right)}}\, du}{4}

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

          Then let du=sin(u)dudu = - \sin{\left(u \right)} du and substitute du- du:

          (1u)du\int \left(- \frac{1}{u}\right)\, du

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

            1udu=1udu\int \frac{1}{u}\, du = - \int \frac{1}{u}\, du

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

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

          Now substitute uu back in:

          log(cos(u))- \log{\left(\cos{\left(u \right)} \right)}

        So, the result is: log(cos(u))4- \frac{\log{\left(\cos{\left(u \right)} \right)}}{4}

      Now substitute uu back in:

      log(cos(4x2))4- \frac{\log{\left(\cos{\left(4 x - 2 \right)} \right)}}{4}

  3. Now simplify:

    log(cos(4x2))4- \frac{\log{\left(\cos{\left(4 x - 2 \right)} \right)}}{4}

  4. Add the constant of integration:

    log(cos(4x2))4+constant- \frac{\log{\left(\cos{\left(4 x - 2 \right)} \right)}}{4}+ \mathrm{constant}


The answer is:

log(cos(4x2))4+constant- \frac{\log{\left(\cos{\left(4 x - 2 \right)} \right)}}{4}+ \mathrm{constant}

The answer (Indefinite) [src]
  /                                       
 |                       log(cos(4*x - 2))
 | tan(4*x - 2) dx = C - -----------------
 |                               4        
/                                         
tan(4x2)dx=Clog(cos(4x2))4\int \tan{\left(4 x - 2 \right)}\, dx = C - \frac{\log{\left(\cos{\left(4 x - 2 \right)} \right)}}{4}
The graph
1.03.01.21.41.61.82.02.22.42.62.8-2000010000
The answer [src]
     /       2   \      /       2    \
  log\1 + tan (2)/   log\1 + tan (10)/
- ---------------- + -----------------
         8                   8        
log(1+tan2(2))8+log(tan2(10)+1)8- \frac{\log{\left(1 + \tan^{2}{\left(2 \right)} \right)}}{8} + \frac{\log{\left(\tan^{2}{\left(10 \right)} + 1 \right)}}{8}
=
=
     /       2   \      /       2    \
  log\1 + tan (2)/   log\1 + tan (10)/
- ---------------- + -----------------
         8                   8        
log(1+tan2(2))8+log(tan2(10)+1)8- \frac{\log{\left(1 + \tan^{2}{\left(2 \right)} \right)}}{8} + \frac{\log{\left(\tan^{2}{\left(10 \right)} + 1 \right)}}{8}
-log(1 + tan(2)^2)/8 + log(1 + tan(10)^2)/8
Numerical answer [src]
1.98789651502355
1.98789651502355

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