z*cos(z)
Apply the product rule:
f(z)=zf{\left(z \right)} = zf(z)=z; to find ddzf(z)\frac{d}{d z} f{\left(z \right)}dzdf(z):
Apply the power rule: zzz goes to 111
g(z)=cos(z)g{\left(z \right)} = \cos{\left(z \right)}g(z)=cos(z); to find ddzg(z)\frac{d}{d z} g{\left(z \right)}dzdg(z):
The derivative of cosine is negative sine:
The result is: −zsin(z)+cos(z)- z \sin{\left(z \right)} + \cos{\left(z \right)}−zsin(z)+cos(z)
The answer is:
-z*sin(z) + cos(z)
-(2*sin(z) + z*cos(z))
-3*cos(z) + z*sin(z)