Mister Exam

Derivative of x*cos(x)

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

The graph:

from to

Piecewise:

The solution

You have entered [src]
x*cos(x)
xcos(x)x \cos{\left(x \right)}
d           
--(x*cos(x))
dx          
ddxxcos(x)\frac{d}{d x} x \cos{\left(x \right)}
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)=cos(x)g{\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)}

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


The answer is:

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

The first derivative [src]
-x*sin(x) + cos(x)
xsin(x)+cos(x)- x \sin{\left(x \right)} + \cos{\left(x \right)}
The second derivative [src]
-(2*sin(x) + x*cos(x))
(xcos(x)+2sin(x))- (x \cos{\left(x \right)} + 2 \sin{\left(x \right)})
The third derivative [src]
-3*cos(x) + x*sin(x)
xsin(x)3cos(x)x \sin{\left(x \right)} - 3 \cos{\left(x \right)}