(1)∵y=log4x3?log4x2=log4x,∴y′=(log4x)′= 1 xln4 ;(2)∵y= 2x2+1 x ?2x=2x+ 1 x -2x= 1 x ,∴y′=( 1 x )′=- 1 x2 ;(3)∵y=-2sin x 2 (2sin2 x 4 -1)=2sin x 2 (1-2sin2 x 4 )=2sin x 2 cos x 2 =sinx.∴y′=(sin x)′=cos x.