Mister Exam

Derivative of (-ln2)cos(logx)²

Function f() - derivative -N order at the point
v

The graph:

from to

Piecewise:

The solution

You have entered [src]
           2        
-log(2)*cos (log(x))
log(2)cos2(log(x))- \log{\left(2 \right)} \cos^{2}{\left(\log{\left(x \right)} \right)}
d /           2        \
--\-log(2)*cos (log(x))/
dx                      
ddxlog(2)cos2(log(x))\frac{d}{d x} - \log{\left(2 \right)} \cos^{2}{\left(\log{\left(x \right)} \right)}
Detail solution
  1. The derivative of a constant times a function is the constant times the derivative of the function.

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

    2. Apply the power rule: u2u^{2} goes to 2u2 u

    3. Then, apply the chain rule. Multiply by ddxcos(log(x))\frac{d}{d x} \cos{\left(\log{\left(x \right)} \right)}:

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

      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 ddxlog(x)\frac{d}{d x} \log{\left(x \right)}:

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

        The result of the chain rule is:

        sin(log(x))x- \frac{\sin{\left(\log{\left(x \right)} \right)}}{x}

      The result of the chain rule is:

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

    So, the result is: 2log(2)sin(log(x))cos(log(x))x\frac{2 \log{\left(2 \right)} \sin{\left(\log{\left(x \right)} \right)} \cos{\left(\log{\left(x \right)} \right)}}{x}

  2. Now simplify:

    log(2)sin(2log(x))x\frac{\log{\left(2 \right)} \sin{\left(2 \log{\left(x \right)} \right)}}{x}


The answer is:

log(2)sin(2log(x))x\frac{\log{\left(2 \right)} \sin{\left(2 \log{\left(x \right)} \right)}}{x}

The graph
02468-8-6-4-2-1010-1010
The first derivative [src]
2*cos(log(x))*log(2)*sin(log(x))
--------------------------------
               x                
2log(2)sin(log(x))cos(log(x))x\frac{2 \log{\left(2 \right)} \sin{\left(\log{\left(x \right)} \right)} \cos{\left(\log{\left(x \right)} \right)}}{x}
The second derivative [src]
   /   2              2                                  \       
-2*\sin (log(x)) - cos (log(x)) + cos(log(x))*sin(log(x))/*log(2)
-----------------------------------------------------------------
                                 2                               
                                x                                
2(sin2(log(x))+sin(log(x))cos(log(x))cos2(log(x)))log(2)x2- \frac{2 \left(\sin^{2}{\left(\log{\left(x \right)} \right)} + \sin{\left(\log{\left(x \right)} \right)} \cos{\left(\log{\left(x \right)} \right)} - \cos^{2}{\left(\log{\left(x \right)} \right)}\right) \log{\left(2 \right)}}{x^{2}}
The third derivative [src]
   /       2                2                                    \       
-2*\- 3*sin (log(x)) + 3*cos (log(x)) + 2*cos(log(x))*sin(log(x))/*log(2)
-------------------------------------------------------------------------
                                     3                                   
                                    x                                    
2(3sin2(log(x))+2sin(log(x))cos(log(x))+3cos2(log(x)))log(2)x3- \frac{2 \left(- 3 \sin^{2}{\left(\log{\left(x \right)} \right)} + 2 \sin{\left(\log{\left(x \right)} \right)} \cos{\left(\log{\left(x \right)} \right)} + 3 \cos^{2}{\left(\log{\left(x \right)} \right)}\right) \log{\left(2 \right)}}{x^{3}}
The graph
Derivative of (-ln2)cos(logx)²