(1)y=根号2x+sinx
y'=1/(2√2x)+cosx
(2)y'=cosxlnx+sinx/x
(3)y'=(x^2+1-2x^2)/(x^2+1)^2=(1-x^2)/(x^2+1)^2
(4)y'=cosx/sinx=cotx