问题
选择题
曲线y=x3+11在点P(1,12)处的切线与y轴交点的纵坐标是( )
A.-9
B.-3
C.9
D.15
答案
∵y=x3+11∴y'=3x2
则y'|x=1=3x2|x=1=3
∴曲线y=x3+11在点P(1,12)处的切线方程为y-12=3(x-1)即3x-y+9=0
令x=0解得y=9
∴曲线y=x3+11在点P(1,12)处的切线与y轴交点的纵坐标是9
故选C
曲线y=x3+11在点P(1,12)处的切线与y轴交点的纵坐标是( )
A.-9
B.-3
C.9
D.15
∵y=x3+11∴y'=3x2
则y'|x=1=3x2|x=1=3
∴曲线y=x3+11在点P(1,12)处的切线方程为y-12=3(x-1)即3x-y+9=0
令x=0解得y=9
∴曲线y=x3+11在点P(1,12)处的切线与y轴交点的纵坐标是9
故选C