Mister Exam

Derivative of ycos(y)

Function f() - derivative -N order at the point
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The graph:

from to

Piecewise:

The solution

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

    ddyf(y)g(y)=f(y)ddyg(y)+g(y)ddyf(y)\frac{d}{d y} f{\left(y \right)} g{\left(y \right)} = f{\left(y \right)} \frac{d}{d y} g{\left(y \right)} + g{\left(y \right)} \frac{d}{d y} f{\left(y \right)}

    f(y)=yf{\left(y \right)} = y; to find ddyf(y)\frac{d}{d y} f{\left(y \right)}:

    1. Apply the power rule: yy goes to 11

    g(y)=cos(y)g{\left(y \right)} = \cos{\left(y \right)}; to find ddyg(y)\frac{d}{d y} g{\left(y \right)}:

    1. The derivative of cosine is negative sine:

      ddycos(y)=sin(y)\frac{d}{d y} \cos{\left(y \right)} = - \sin{\left(y \right)}

    The result is: ysin(y)+cos(y)- y \sin{\left(y \right)} + \cos{\left(y \right)}


The answer is:

ysin(y)+cos(y)- y \sin{\left(y \right)} + \cos{\left(y \right)}

The graph
02468-8-6-4-2-1010-2020
The first derivative [src]
-y*sin(y) + cos(y)
ysin(y)+cos(y)- y \sin{\left(y \right)} + \cos{\left(y \right)}
The second derivative [src]
-(2*sin(y) + y*cos(y))
(ycos(y)+2sin(y))- (y \cos{\left(y \right)} + 2 \sin{\left(y \right)})
The third derivative [src]
-3*cos(y) + y*sin(y)
ysin(y)3cos(y)y \sin{\left(y \right)} - 3 \cos{\left(y \right)}