Mister Exam

Derivative of tgx+tg^3x

Function f() - derivative -N order at the point
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            3   
tan(x) + tan (x)
tan3(x)+tan(x)\tan^{3}{\left(x \right)} + \tan{\left(x \right)}
d /            3   \
--\tan(x) + tan (x)/
dx                  
ddx(tan3(x)+tan(x))\frac{d}{d x} \left(\tan^{3}{\left(x \right)} + \tan{\left(x \right)}\right)
Detail solution
  1. Differentiate tan3(x)+tan(x)\tan^{3}{\left(x \right)} + \tan{\left(x \right)} term by term:

    1. Rewrite the function to be differentiated:

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

    2. Apply the quotient rule, which is:

      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)} and g(x)=cos(x)g{\left(x \right)} = \cos{\left(x \right)}.

      To find ddxf(x)\frac{d}{d x} f{\left(x \right)}:

      1. The derivative of sine is cosine:

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

      To find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

      1. The derivative of cosine is negative sine:

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

      Now plug in to the quotient rule:

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

    3. Let u=tan(x)u = \tan{\left(x \right)}.

    4. Apply the power rule: u3u^{3} goes to 3u23 u^{2}

    5. Then, apply the chain rule. Multiply by ddxtan(x)\frac{d}{d x} \tan{\left(x \right)}:

      1. ddxtan(x)=1cos2(x)\frac{d}{d x} \tan{\left(x \right)} = \frac{1}{\cos^{2}{\left(x \right)}}

      The result of the chain rule is:

      3(sin2(x)+cos2(x))tan2(x)cos2(x)\frac{3 \left(\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) \tan^{2}{\left(x \right)}}{\cos^{2}{\left(x \right)}}

    The result is: 3(sin2(x)+cos2(x))tan2(x)cos2(x)+sin2(x)+cos2(x)cos2(x)\frac{3 \left(\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) \tan^{2}{\left(x \right)}}{\cos^{2}{\left(x \right)}} + \frac{\sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}}{\cos^{2}{\left(x \right)}}

  2. Now simplify:

    3tan2(x)+1cos2(x)\frac{3 \tan^{2}{\left(x \right)} + 1}{\cos^{2}{\left(x \right)}}


The answer is:

3tan2(x)+1cos2(x)\frac{3 \tan^{2}{\left(x \right)} + 1}{\cos^{2}{\left(x \right)}}

The graph
02468-8-6-4-2-10104000000-2000000
The first derivative [src]
       2         2    /         2   \
1 + tan (x) + tan (x)*\3 + 3*tan (x)/
(3tan2(x)+3)tan2(x)+tan2(x)+1\left(3 \tan^{2}{\left(x \right)} + 3\right) \tan^{2}{\left(x \right)} + \tan^{2}{\left(x \right)} + 1
The second derivative [src]
  /       2   \ /         2   \       
2*\1 + tan (x)/*\4 + 6*tan (x)/*tan(x)
2(tan2(x)+1)(6tan2(x)+4)tan(x)2 \left(\tan^{2}{\left(x \right)} + 1\right) \left(6 \tan^{2}{\left(x \right)} + 4\right) \tan{\left(x \right)}
The third derivative [src]
                /                   2                                                   \
  /       2   \ |      /       2   \         2           4            2    /       2   \|
2*\1 + tan (x)/*\1 + 3*\1 + tan (x)/  + 3*tan (x) + 6*tan (x) + 21*tan (x)*\1 + tan (x)//
2(tan2(x)+1)(6tan4(x)+21(tan2(x)+1)tan2(x)+3(tan2(x)+1)2+3tan2(x)+1)2 \left(\tan^{2}{\left(x \right)} + 1\right) \left(6 \tan^{4}{\left(x \right)} + 21 \left(\tan^{2}{\left(x \right)} + 1\right) \tan^{2}{\left(x \right)} + 3 \left(\tan^{2}{\left(x \right)} + 1\right)^{2} + 3 \tan^{2}{\left(x \right)} + 1\right)
The graph
Derivative of tgx+tg^3x