Question

若曲线y=x⁴的一条切线l的斜率是4，则切线l的方程为

A.4x-y-3=0                                       B.x+4y-5=0

C.4x-y+3=0                                       D.x+4y+3=0

Answer 1

A

解析:∵y′=(x⁴)′=4x³,且l的斜率是4,∴4x³=4.∴x=1.

y=1⁴=1,∴切点为(1,1).

则l的方程为4(x-1)=y-1,即4x-y-3=0.

选A.