(1) y'=3/5x^(-2/5)
y"=3/5(-2/5)x^(-7/5)
-6/25x^(-7/5)
(2) y'=-2xe^(-x^2)
y"=-2[e^(-x^2)+x(-2x)e^(-x^2)]
=-2e^(-x^2)(1-2x^2)
(3) y'=acosax-bsinbx
y"=-a^2sinax-b^2cosbx
(4) y'=e^xsinx+e^xcosx
=e^x(sinx+cosx)
y"=e^x(sinx+cosx)+e^x(cosx-sinx)
=2cosxe^x
(5) y'=2/(2x)
=1/x
y"=-1/x^2
(6) y'=ln(x+2)+x/(x+2)
y"=1/(x+2)+[(x+2)-x]/(x+2)^2
=(x+2)/(x+2)^2+2/(x+2)^2
=(x+2+2)/(x+2)^2
=(x+4)/(x+2)^2