1) у= tgx³

y' = 3x²/cos²x³

2) y=2arctg3/x

y' = -2*(3/x²)/(1+(3/x)²) = -6/(x²(1+(3/x)²)

3) y=2arcctg lnx/x

y' = 2*(1/x)*(-1/x²)/(1/(lnx/x)) = -2/(x³*lnx/x)