1
切线斜率k=y'=cosx y=-sinx+C , 过(π/6,1) C=3/2
y=-sinx+3/2
2
y=e^x 切线斜率k=y'=e^x 法线斜率k'=-1/k=-e^(-x)
(1,e) 切线方程 k=e y-e=e(x-1)
法线方程k'=-1/e y-e=-(x-1)/e
3
f(x)（0,2）内可导数,连续
f'(ξ)=[f(2)-f(0)]/(2-0)=6/2=3
f(x)=x^3-x, f'(x)=3x^2-1 3x^2-1=3 x^2=4/3 x=2√3/3
ξ=2√3/3