Sr Examen

Derivada de y=(tgx)/(lnx)

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

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Definida a trozos:

Solución

Ha introducido [src]
tan(x)
------
log(x)
tan(x)log(x)\frac{\tan{\left(x \right)}}{\log{\left(x \right)}}
tan(x)/log(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)=tan(x)f{\left(x \right)} = \tan{\left(x \right)} y g(x)=log(x)g{\left(x \right)} = \log{\left(x \right)}.

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

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

    1. Derivado log(x)\log{\left(x \right)} es 1x\frac{1}{x}.

    Ahora aplicamos la regla de la derivada de una divesión:

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

  2. Simplificamos:

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


Respuesta:

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

Gráfica
02468-8-6-4-2-1010-10001000
Primera derivada [src]
       2               
1 + tan (x)     tan(x) 
----------- - ---------
   log(x)          2   
              x*log (x)
tan2(x)+1log(x)tan(x)xlog(x)2\frac{\tan^{2}{\left(x \right)} + 1}{\log{\left(x \right)}} - \frac{\tan{\left(x \right)}}{x \log{\left(x \right)}^{2}}
Segunda derivada [src]
                                           /      2   \       
                           /       2   \   |1 + ------|*tan(x)
  /       2   \          2*\1 + tan (x)/   \    log(x)/       
2*\1 + tan (x)/*tan(x) - --------------- + -------------------
                             x*log(x)            2            
                                                x *log(x)     
--------------------------------------------------------------
                            log(x)                            
2(tan2(x)+1)tan(x)2(tan2(x)+1)xlog(x)+(1+2log(x))tan(x)x2log(x)log(x)\frac{2 \left(\tan^{2}{\left(x \right)} + 1\right) \tan{\left(x \right)} - \frac{2 \left(\tan^{2}{\left(x \right)} + 1\right)}{x \log{\left(x \right)}} + \frac{\left(1 + \frac{2}{\log{\left(x \right)}}\right) \tan{\left(x \right)}}{x^{2} \log{\left(x \right)}}}{\log{\left(x \right)}}
Tercera derivada [src]
                                                             /      3         3   \                                      
                                                           2*|1 + ------ + -------|*tan(x)     /       2   \ /      2   \
                                    /       2   \            |    log(x)      2   |          3*\1 + tan (x)/*|1 + ------|
  /       2   \ /         2   \   6*\1 + tan (x)/*tan(x)     \             log (x)/                          \    log(x)/
2*\1 + tan (x)/*\1 + 3*tan (x)/ - ---------------------- - ------------------------------- + ----------------------------
                                         x*log(x)                      3                               2                 
                                                                      x *log(x)                       x *log(x)          
-------------------------------------------------------------------------------------------------------------------------
                                                          log(x)                                                         
2(tan2(x)+1)(3tan2(x)+1)6(tan2(x)+1)tan(x)xlog(x)+3(1+2log(x))(tan2(x)+1)x2log(x)2(1+3log(x)+3log(x)2)tan(x)x3log(x)log(x)\frac{2 \left(\tan^{2}{\left(x \right)} + 1\right) \left(3 \tan^{2}{\left(x \right)} + 1\right) - \frac{6 \left(\tan^{2}{\left(x \right)} + 1\right) \tan{\left(x \right)}}{x \log{\left(x \right)}} + \frac{3 \left(1 + \frac{2}{\log{\left(x \right)}}\right) \left(\tan^{2}{\left(x \right)} + 1\right)}{x^{2} \log{\left(x \right)}} - \frac{2 \left(1 + \frac{3}{\log{\left(x \right)}} + \frac{3}{\log{\left(x \right)}^{2}}\right) \tan{\left(x \right)}}{x^{3} \log{\left(x \right)}}}{\log{\left(x \right)}}
Gráfico
Derivada de y=(tgx)/(lnx)