求下列函数的导数：（1）y=5x^2-4x+1 (2)y=(2x^2-1)(3x^2+1) (3)y=(x+cosx）/（x+sinx)

1. y' = 10x - 42. y' = 4x(3x^2 - 1) + 6x(2x^2 - 1) = 24x^2 - 10x 3. y' = [(1-sinx)(x+sinx) - (1+cosx)(x+cosx)]/(x+sinx)^2= (sinx - xsinx - cosx - xcosx - 1)/(x+sinx)^2