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Derivative of x*(cos(logx)+sin(logx))

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

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The solution

You have entered [src]
x*(cos(log(x)) + sin(log(x)))
x(sin(log(x))+cos(log(x)))x \left(\sin{\left(\log{\left(x \right)} \right)} + \cos{\left(\log{\left(x \right)} \right)}\right)
x*(cos(log(x)) + sin(log(x)))
Detail solution
  1. Apply the product rule:

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

    1. Apply the power rule: xx goes to 11

    g(x)=sin(log(x))+cos(log(x))g{\left(x \right)} = \sin{\left(\log{\left(x \right)} \right)} + \cos{\left(\log{\left(x \right)} \right)}; to find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

    1. Differentiate sin(log(x))+cos(log(x))\sin{\left(\log{\left(x \right)} \right)} + \cos{\left(\log{\left(x \right)} \right)} term by term:

      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}

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

      5. The derivative of sine is cosine:

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

      6. 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:

        cos(log(x))x\frac{\cos{\left(\log{\left(x \right)} \right)}}{x}

      The result is: sin(log(x))x+cos(log(x))x- \frac{\sin{\left(\log{\left(x \right)} \right)}}{x} + \frac{\cos{\left(\log{\left(x \right)} \right)}}{x}

    The result is: x(sin(log(x))x+cos(log(x))x)+sin(log(x))+cos(log(x))x \left(- \frac{\sin{\left(\log{\left(x \right)} \right)}}{x} + \frac{\cos{\left(\log{\left(x \right)} \right)}}{x}\right) + \sin{\left(\log{\left(x \right)} \right)} + \cos{\left(\log{\left(x \right)} \right)}

  2. Now simplify:

    2cos(log(x))2 \cos{\left(\log{\left(x \right)} \right)}


The answer is:

2cos(log(x))2 \cos{\left(\log{\left(x \right)} \right)}

The graph
02468-8-6-4-2-10105-5
The first derivative [src]
  /cos(log(x))   sin(log(x))\                            
x*|----------- - -----------| + cos(log(x)) + sin(log(x))
  \     x             x     /                            
x(sin(log(x))x+cos(log(x))x)+sin(log(x))+cos(log(x))x \left(- \frac{\sin{\left(\log{\left(x \right)} \right)}}{x} + \frac{\cos{\left(\log{\left(x \right)} \right)}}{x}\right) + \sin{\left(\log{\left(x \right)} \right)} + \cos{\left(\log{\left(x \right)} \right)}
The second derivative [src]
-2*sin(log(x))
--------------
      x       
2sin(log(x))x- \frac{2 \sin{\left(\log{\left(x \right)} \right)}}{x}
The third derivative [src]
2*(-cos(log(x)) + sin(log(x)))
------------------------------
               2              
              x               
2(sin(log(x))cos(log(x)))x2\frac{2 \left(\sin{\left(\log{\left(x \right)} \right)} - \cos{\left(\log{\left(x \right)} \right)}\right)}{x^{2}}