與直線y=4x-1平行的曲線y=x3+x的切線方程是() A. 4x-y=0B. 4x-y+2=0或4x-y-2=0C. 4x-y-2=0D. 4x-y=0或4x-y-4=0

與直線y=4x-1平行的曲線y=x3+x的切線方程是() A. 4x-y=0B. 4x-y+2=0或4x-y-2=0C. 4x-y-2=0D. 4x-y=0或4x-y-4=0

∵y=x3+x∴y′=3x2+1.令y′=4⇒x2=1⇒x=±1.把x=1代入y=x3+x得:y=2.所以切線方程為:y-2=4(x-1)⇒4x-y-2=0;把x=-1代入y=x3+x得:y=-2,所以切線方程為:y+2=4(x+1)⇒4x-y+2=0.故選B.