Mister Exam

Derivative of cos(x)*log(x)

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

The graph:

from to

Piecewise:

The solution

You have entered [src]
cos(x)*log(x)
log(x)cos(x)\log{\left(x \right)} \cos{\left(x \right)}
cos(x)*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)=cos(x)f{\left(x \right)} = \cos{\left(x \right)}; to find ddxf(x)\frac{d}{d x} f{\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)}

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

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

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


The answer is:

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

The graph
02468-8-6-4-2-101020-10
The first derivative [src]
cos(x)                
------ - log(x)*sin(x)
  x                   
log(x)sin(x)+cos(x)x- \log{\left(x \right)} \sin{\left(x \right)} + \frac{\cos{\left(x \right)}}{x}
The second derivative [src]
 /cos(x)                   2*sin(x)\
-|------ + cos(x)*log(x) + --------|
 |   2                        x    |
 \  x                              /
(log(x)cos(x)+2sin(x)x+cos(x)x2)- (\log{\left(x \right)} \cos{\left(x \right)} + \frac{2 \sin{\left(x \right)}}{x} + \frac{\cos{\left(x \right)}}{x^{2}})
The third derivative [src]
                3*cos(x)   2*cos(x)   3*sin(x)
log(x)*sin(x) - -------- + -------- + --------
                   x           3          2   
                              x          x    
log(x)sin(x)3cos(x)x+3sin(x)x2+2cos(x)x3\log{\left(x \right)} \sin{\left(x \right)} - \frac{3 \cos{\left(x \right)}}{x} + \frac{3 \sin{\left(x \right)}}{x^{2}} + \frac{2 \cos{\left(x \right)}}{x^{3}}
The graph
Derivative of cos(x)*log(x)