Найти производную функции. а)f(x)=1/3x^3+x^2+2x б)ф(x)=2/x^3-x

A) 
f ' (x) = 1/3*3x^2 + 2x + 2 = x^2 + 2x + 2 

b)
f ' (x) = (2/x^3 - x) ' = 2*(1/x^3) ' - (x)' = 2*(x^(-3))' - 1 = 
= - 3*2*x^(-4) - 1 = - 6x^(-4) - 1