若曲线y=x4+mx在x=-1处的切线方程为2x+y+3=0,则m等于( )
A.-1
B.1
C.-2
D.2
∵y=x4+mx,
∴y′=4x3+m,
∴曲线y=x4+mx在x=-1处的切线斜率
k=-4+m,
∴-4+m=-2.m=2,
故选D.
若曲线y=x4+mx在x=-1处的切线方程为2x+y+3=0,则m等于( )
A.-1
B.1
C.-2
D.2
∵y=x4+mx,
∴y′=4x3+m,
∴曲线y=x4+mx在x=-1处的切线斜率
k=-4+m,
∴-4+m=-2.m=2,
故选D.