Mister Exam

Derivative of xsin^2x

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

The graph:

from to

Piecewise:

The solution

You have entered [src]
     2   
x*sin (x)
xsin2(x)x \sin^{2}{\left(x \right)}
d /     2   \
--\x*sin (x)/
dx           
ddxxsin2(x)\frac{d}{d x} x \sin^{2}{\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)=sin2(x)g{\left(x \right)} = \sin^{2}{\left(x \right)}; to find ddxg(x)\frac{d}{d x} g{\left(x \right)}:

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

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

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

      1. The derivative of sine is cosine:

        ddxsin(x)=cos(x)\frac{d}{d x} \sin{\left(x \right)} = \cos{\left(x \right)}

      The result of the chain rule is:

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

    The result is: 2xsin(x)cos(x)+sin2(x)2 x \sin{\left(x \right)} \cos{\left(x \right)} + \sin^{2}{\left(x \right)}

  2. Now simplify:

    xsin(2x)cos(2x)2+12x \sin{\left(2 x \right)} - \frac{\cos{\left(2 x \right)}}{2} + \frac{1}{2}


The answer is:

xsin(2x)cos(2x)2+12x \sin{\left(2 x \right)} - \frac{\cos{\left(2 x \right)}}{2} + \frac{1}{2}

The graph
02468-8-6-4-2-1010-2020
The first derivative [src]
   2                       
sin (x) + 2*x*cos(x)*sin(x)
2xsin(x)cos(x)+sin2(x)2 x \sin{\left(x \right)} \cos{\left(x \right)} + \sin^{2}{\left(x \right)}
The second derivative [src]
  /    /   2         2   \                  \
2*\- x*\sin (x) - cos (x)/ + 2*cos(x)*sin(x)/
2(x(sin2(x)cos2(x))+2sin(x)cos(x))2 \left(- x \left(\sin^{2}{\left(x \right)} - \cos^{2}{\left(x \right)}\right) + 2 \sin{\left(x \right)} \cos{\left(x \right)}\right)
The third derivative [src]
  /       2           2                       \
2*\- 3*sin (x) + 3*cos (x) - 4*x*cos(x)*sin(x)/
2(4xsin(x)cos(x)3sin2(x)+3cos2(x))2 \left(- 4 x \sin{\left(x \right)} \cos{\left(x \right)} - 3 \sin^{2}{\left(x \right)} + 3 \cos^{2}{\left(x \right)}\right)
The graph
Derivative of xsin^2x