1) y=x+ctg(1/x)
у' = 1 + 1/Sin²(1/x) * 1/x² = 1 + 1/(x²*sin(1/x) )
y'= 1 + x⁻²*Sin⁻¹(1/x)
y'' = (x⁻²)' *Sin⁻¹(1/x) + x⁻²*(Sin⁻¹(1/x))' =
= -2x⁻³*Sin(1/x) + x⁻²* (-Sin⁻²(1/x)*Cos(1/x)*(-1/x²) ) =
=-2Sin(1/x) /x³ +Cos(1/x)/ (x²*Sin²(1/x))
2) y= 3/x*arcSinx/3
y' =(3/x)' *arcSinx/3 + 3/x*(arcSinx/3)' =
= -3/х² * arcSinx/3 + 3/x*1/√(1 - x²/9) * (1/3)=
=-3arcSinx/3 /х² + 1/√(1 - х²/9)
y'' = (-x²/√(1 - x²/9) -6x*arcSinx/3 )/x⁴