因为(lnx)'=1/x
所以[ln(1+sin2x^2)]' = [1/(1+sin2x^2)]*(1+sin2x^2)'
=[1/(1+sin2x^2)]*(sin2x^2)'
=[1/(1+sin2x^2)]*(cos2x^2)*(2x^2)'
= [cos2x^2/(1+sin2x^2)]*4x
= 4xcos2x^2/(1+sin2x^2)