(2)y′=(sin x-x+ln x)′=(sin x)′+(-x)′+(ln x)′=cos x-1+;
(3)
=(x4)′+(6x3)′+(-ex)′+
=4x3+18x2-ex.
10答案:解:(1)由题意f′(x)=3x2-2,f′(1)=1,
∴点(1,-1)处的切线的斜率k=1,
其方程为y+1=x-1,即x-y-2=0.
(2)设切点为(x0,y0),则y0=x03-2x0,
则切点处的导数值f′(x0)=3x02-2;
若点(1,-1)为切点,由(1)知切线方程为x-y-2=0;若点(1,-1)不为切点,则
3x02-2=(x0≠1),
即3x02-2=,
∴3x03-2x0-3x02+1=x03-2x0,∴2x03-3x02+1=0,
即(x0-1)(2x02-x0-1)=0,
∴x0=1或x0=,其中x0=1舍去,
则切点坐标为,
∴斜率为,
∴切线方程为5x+4y-1=0,
∴过点(1,-1)的切线方程为x-y-2=0或5x+4y-1=0.