Найдите производную:

A)
f (x) =(x⁴ -3/x +(1/2)*x² -(1/3)*x³ ) = 
(x⁴) -(3*x^(-1)) +((1/2)*x²) -((1/3)*x³)=
4x³ -3*(-1)*x^(-2)  +(1/2)*2x -(1/3)*3x²=4x³ +3/x²  +x -x² .
B)
f(x) =( (cos3x)/x ) =((cos3x)*x -(x)*(cos3x)/x²=
(-sin3x*(3x)*x -cos3x)/x²= -(3x*sin3x +cos3x)/x².
C)
f (x) =( (x²+x√7)⁷ ) =7*(x²+x√7)⁶ *(x²+x√7) =7*(x²+x√7)⁶ *(2x+√7).