Sr Examen

Derivada de (x/tgx)*sin(7x)

Función f() - derivada -er orden en el punto
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Gráfico:

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Solución

Ha introducido [src]
  x            
------*sin(7*x)
tan(x)         
xtan(x)sin(7x)\frac{x}{\tan{\left(x \right)}} \sin{\left(7 x \right)}
(x/tan(x))*sin(7*x)
Solución detallada
  1. Se aplica la regla de la derivada parcial:

    ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)g2(x)\frac{d}{d x} \frac{f{\left(x \right)}}{g{\left(x \right)}} = \frac{- f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}}{g^{2}{\left(x \right)}}

    f(x)=xsin(7x)f{\left(x \right)} = x \sin{\left(7 x \right)} y g(x)=tan(x)g{\left(x \right)} = \tan{\left(x \right)}.

    Para calcular ddxf(x)\frac{d}{d x} f{\left(x \right)}:

    1. Se aplica la regla de la derivada de una multiplicación:

      ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)\frac{d}{d x} f{\left(x \right)} g{\left(x \right)} = f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}

      f(x)=xf{\left(x \right)} = x; calculamos ddxf(x)\frac{d}{d x} f{\left(x \right)}:

      1. Según el principio, aplicamos: xx tenemos 11

      g(x)=sin(7x)g{\left(x \right)} = \sin{\left(7 x \right)}; calculamos ddxg(x)\frac{d}{d x} g{\left(x \right)}:

      1. Sustituimos u=7xu = 7 x.

      2. La derivada del seno es igual al coseno:

        ddusin(u)=cos(u)\frac{d}{d u} \sin{\left(u \right)} = \cos{\left(u \right)}

      3. Luego se aplica una cadena de reglas. Multiplicamos por ddx7x\frac{d}{d x} 7 x:

        1. La derivada del producto de una constante por función es igual al producto de esta constante por la derivada de esta función.

          1. Según el principio, aplicamos: xx tenemos 11

          Entonces, como resultado: 77

        Como resultado de la secuencia de reglas:

        7cos(7x)7 \cos{\left(7 x \right)}

      Como resultado de: 7xcos(7x)+sin(7x)7 x \cos{\left(7 x \right)} + \sin{\left(7 x \right)}

    Para calcular ddxg(x)\frac{d}{d x} g{\left(x \right)}:

    1. Reescribimos las funciones para diferenciar:

      tan(x)=sin(x)cos(x)\tan{\left(x \right)} = \frac{\sin{\left(x \right)}}{\cos{\left(x \right)}}

    2. Se aplica la regla de la derivada parcial:

      ddxf(x)g(x)=f(x)ddxg(x)+g(x)ddxf(x)g2(x)\frac{d}{d x} \frac{f{\left(x \right)}}{g{\left(x \right)}} = \frac{- f{\left(x \right)} \frac{d}{d x} g{\left(x \right)} + g{\left(x \right)} \frac{d}{d x} f{\left(x \right)}}{g^{2}{\left(x \right)}}

      f(x)=sin(x)f{\left(x \right)} = \sin{\left(x \right)} y g(x)=cos(x)g{\left(x \right)} = \cos{\left(x \right)}.

      Para calcular ddxf(x)\frac{d}{d x} f{\left(x \right)}:

      1. La derivada del seno es igual al coseno:

        ddxsin(x)=cos(x)\frac{d}{d x} \sin{\left(x \right)} = \cos{\left(x \right)}

      Para calcular ddxg(x)\frac{d}{d x} g{\left(x \right)}:

      1. La derivada del coseno es igual a menos el seno:

        ddxcos(x)=sin(x)\frac{d}{d x} \cos{\left(x \right)} = - \sin{\left(x \right)}

      Ahora aplicamos la regla de la derivada de una divesión:

      sin2(x)+cos2(x)cos2(x)\frac{\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}}{\cos^{2}{\left(x \right)}}

    Ahora aplicamos la regla de la derivada de una divesión:

    x(sin2(x)+cos2(x))sin(7x)cos2(x)+(7xcos(7x)+sin(7x))tan(x)tan2(x)\frac{- \frac{x \left(\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) \sin{\left(7 x \right)}}{\cos^{2}{\left(x \right)}} + \left(7 x \cos{\left(7 x \right)} + \sin{\left(7 x \right)}\right) \tan{\left(x \right)}}{\tan^{2}{\left(x \right)}}

  2. Simplificamos:

    7xsin(5x)+4xsin(7x)7xsin(9x)cos(5x)+cos(9x)2cos(2x)2\frac{7 x \sin{\left(5 x \right)} + 4 x \sin{\left(7 x \right)} - 7 x \sin{\left(9 x \right)} - \cos{\left(5 x \right)} + \cos{\left(9 x \right)}}{2 \cos{\left(2 x \right)} - 2}


Respuesta:

7xsin(5x)+4xsin(7x)7xsin(9x)cos(5x)+cos(9x)2cos(2x)2\frac{7 x \sin{\left(5 x \right)} + 4 x \sin{\left(7 x \right)} - 7 x \sin{\left(9 x \right)} - \cos{\left(5 x \right)} + \cos{\left(9 x \right)}}{2 \cos{\left(2 x \right)} - 2}

Gráfica
02468-8-6-4-2-1010-500500
Primera derivada [src]
/           /        2   \\                        
|  1      x*\-1 - tan (x)/|            7*x*cos(7*x)
|------ + ----------------|*sin(7*x) + ------------
|tan(x)          2        |               tan(x)   
\             tan (x)     /                        
7xcos(7x)tan(x)+(x(tan2(x)1)tan2(x)+1tan(x))sin(7x)\frac{7 x \cos{\left(7 x \right)}}{\tan{\left(x \right)}} + \left(\frac{x \left(- \tan^{2}{\left(x \right)} - 1\right)}{\tan^{2}{\left(x \right)}} + \frac{1}{\tan{\left(x \right)}}\right) \sin{\left(7 x \right)}
Segunda derivada [src]
                    /       /       2   \\                            /             /            2   \\         
                    |     x*\1 + tan (x)/|              /       2   \ |    1        |     1 + tan (x)||         
-49*x*sin(7*x) - 14*|-1 + ---------------|*cos(7*x) + 2*\1 + tan (x)/*|- ------ + x*|-1 + -----------||*sin(7*x)
                    \          tan(x)    /                            |  tan(x)     |          2     ||         
                                                                      \             \       tan (x)  //         
----------------------------------------------------------------------------------------------------------------
                                                     tan(x)                                                     
49xsin(7x)+2(x(tan2(x)+1tan2(x)1)1tan(x))(tan2(x)+1)sin(7x)14(x(tan2(x)+1)tan(x)1)cos(7x)tan(x)\frac{- 49 x \sin{\left(7 x \right)} + 2 \left(x \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{2}{\left(x \right)}} - 1\right) - \frac{1}{\tan{\left(x \right)}}\right) \left(\tan^{2}{\left(x \right)} + 1\right) \sin{\left(7 x \right)} - 14 \left(\frac{x \left(\tan^{2}{\left(x \right)} + 1\right)}{\tan{\left(x \right)}} - 1\right) \cos{\left(7 x \right)}}{\tan{\left(x \right)}}
Tercera derivada [src]
    /                                                                          /            2   \\                                                                                    /             /            2   \\         
    |                                                            /       2   \ |     1 + tan (x)||                                 /       /       2   \\               /       2   \ |    1        |     1 + tan (x)||         
    |  /                               2                  3\   3*\1 + tan (x)/*|-1 + -----------||                                 |     x*\1 + tan (x)/|            42*\1 + tan (x)/*|- ------ + x*|-1 + -----------||*cos(7*x)
    |  |                  /       2   \      /       2   \ |                   |          2     ||                             147*|-1 + ---------------|*sin(7*x)                    |  tan(x)     |          2     ||         
    |  |         2      5*\1 + tan (x)/    3*\1 + tan (x)/ |                   \       tan (x)  /|            343*x*cos(7*x)       \          tan(x)    /                             \             \       tan (x)  //         
- 2*|x*|2 + 2*tan (x) - ---------------- + ----------------| - ----------------------------------|*sin(7*x) - -------------- + ----------------------------------- + -----------------------------------------------------------
    |  |                       2                  4        |                 tan(x)              |                tan(x)                      tan(x)                                            tan(x)                          
    \  \                    tan (x)            tan (x)     /                                     /                                                                                                                              
343xcos(7x)tan(x)+42(x(tan2(x)+1tan2(x)1)1tan(x))(tan2(x)+1)cos(7x)tan(x)2(x(3(tan2(x)+1)3tan4(x)5(tan2(x)+1)2tan2(x)+2tan2(x)+2)3(tan2(x)+1tan2(x)1)(tan2(x)+1)tan(x))sin(7x)+147(x(tan2(x)+1)tan(x)1)sin(7x)tan(x)- \frac{343 x \cos{\left(7 x \right)}}{\tan{\left(x \right)}} + \frac{42 \left(x \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{2}{\left(x \right)}} - 1\right) - \frac{1}{\tan{\left(x \right)}}\right) \left(\tan^{2}{\left(x \right)} + 1\right) \cos{\left(7 x \right)}}{\tan{\left(x \right)}} - 2 \left(x \left(\frac{3 \left(\tan^{2}{\left(x \right)} + 1\right)^{3}}{\tan^{4}{\left(x \right)}} - \frac{5 \left(\tan^{2}{\left(x \right)} + 1\right)^{2}}{\tan^{2}{\left(x \right)}} + 2 \tan^{2}{\left(x \right)} + 2\right) - \frac{3 \left(\frac{\tan^{2}{\left(x \right)} + 1}{\tan^{2}{\left(x \right)}} - 1\right) \left(\tan^{2}{\left(x \right)} + 1\right)}{\tan{\left(x \right)}}\right) \sin{\left(7 x \right)} + \frac{147 \left(\frac{x \left(\tan^{2}{\left(x \right)} + 1\right)}{\tan{\left(x \right)}} - 1\right) \sin{\left(7 x \right)}}{\tan{\left(x \right)}}
Gráfico
Derivada de (x/tgx)*sin(7x)