Mister Exam

Derivative of logtan(x²)

Function f() - derivative -N order at the point
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The solution

You have entered [src]
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log\tan\x //
log(tan(x2))\log{\left(\tan{\left(x^{2} \right)} \right)}
log(tan(x^2))
Detail solution
  1. Let u=tan(x2)u = \tan{\left(x^{2} \right)}.

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

  3. Then, apply the chain rule. Multiply by ddxtan(x2)\frac{d}{d x} \tan{\left(x^{2} \right)}:

    1. Rewrite the function to be differentiated:

      tan(x2)=sin(x2)cos(x2)\tan{\left(x^{2} \right)} = \frac{\sin{\left(x^{2} \right)}}{\cos{\left(x^{2} \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(x2)f{\left(x \right)} = \sin{\left(x^{2} \right)} and g(x)=cos(x2)g{\left(x \right)} = \cos{\left(x^{2} \right)}.

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

      1. Let u=x2u = x^{2}.

      2. The derivative of sine is cosine:

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

      3. Then, apply the chain rule. Multiply by ddxx2\frac{d}{d x} x^{2}:

        1. Apply the power rule: x2x^{2} goes to 2x2 x

        The result of the chain rule is:

        2xcos(x2)2 x \cos{\left(x^{2} \right)}

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

      1. Let u=x2u = x^{2}.

      2. The derivative of cosine is negative sine:

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

      3. Then, apply the chain rule. Multiply by ddxx2\frac{d}{d x} x^{2}:

        1. Apply the power rule: x2x^{2} goes to 2x2 x

        The result of the chain rule is:

        2xsin(x2)- 2 x \sin{\left(x^{2} \right)}

      Now plug in to the quotient rule:

      2xsin2(x2)+2xcos2(x2)cos2(x2)\frac{2 x \sin^{2}{\left(x^{2} \right)} + 2 x \cos^{2}{\left(x^{2} \right)}}{\cos^{2}{\left(x^{2} \right)}}

    The result of the chain rule is:

    2xsin2(x2)+2xcos2(x2)cos2(x2)tan(x2)\frac{2 x \sin^{2}{\left(x^{2} \right)} + 2 x \cos^{2}{\left(x^{2} \right)}}{\cos^{2}{\left(x^{2} \right)} \tan{\left(x^{2} \right)}}

  4. Now simplify:

    4xsin(2x2)\frac{4 x}{\sin{\left(2 x^{2} \right)}}


The answer is:

4xsin(2x2)\frac{4 x}{\sin{\left(2 x^{2} \right)}}

The graph
02468-8-6-4-2-1010-10001000
The first derivative [src]
    /       2/ 2\\
2*x*\1 + tan \x //
------------------
        / 2\      
     tan\x /      
2x(tan2(x2)+1)tan(x2)\frac{2 x \left(\tan^{2}{\left(x^{2} \right)} + 1\right)}{\tan{\left(x^{2} \right)}}
The second derivative [src]
                 /                    2 /       2/ 2\\\
  /       2/ 2\\ |   1         2   2*x *\1 + tan \x //|
2*\1 + tan \x //*|------- + 4*x  - -------------------|
                 |   / 2\                   2/ 2\     |
                 \tan\x /                tan \x /     /
2(tan2(x2)+1)(2x2(tan2(x2)+1)tan2(x2)+4x2+1tan(x2))2 \left(\tan^{2}{\left(x^{2} \right)} + 1\right) \left(- \frac{2 x^{2} \left(\tan^{2}{\left(x^{2} \right)} + 1\right)}{\tan^{2}{\left(x^{2} \right)}} + 4 x^{2} + \frac{1}{\tan{\left(x^{2} \right)}}\right)
The third derivative [src]
                   /                                                                               2\
                   |      /       2/ 2\\                     2 /       2/ 2\\      2 /       2/ 2\\ |
    /       2/ 2\\ |    3*\1 + tan \x //      2    / 2\   8*x *\1 + tan \x //   4*x *\1 + tan \x // |
4*x*\1 + tan \x //*|6 - ---------------- + 8*x *tan\x / - ------------------- + --------------------|
                   |           2/ 2\                               / 2\                  3/ 2\      |
                   \        tan \x /                            tan\x /               tan \x /      /
4x(tan2(x2)+1)(4x2(tan2(x2)+1)2tan3(x2)8x2(tan2(x2)+1)tan(x2)+8x2tan(x2)3(tan2(x2)+1)tan2(x2)+6)4 x \left(\tan^{2}{\left(x^{2} \right)} + 1\right) \left(\frac{4 x^{2} \left(\tan^{2}{\left(x^{2} \right)} + 1\right)^{2}}{\tan^{3}{\left(x^{2} \right)}} - \frac{8 x^{2} \left(\tan^{2}{\left(x^{2} \right)} + 1\right)}{\tan{\left(x^{2} \right)}} + 8 x^{2} \tan{\left(x^{2} \right)} - \frac{3 \left(\tan^{2}{\left(x^{2} \right)} + 1\right)}{\tan^{2}{\left(x^{2} \right)}} + 6\right)