f(1)=e^1-1-1=e-2
f'(x)=e^x-1
K=f'(1)=e^1-1=e-1
所以切线方程是
y-(e-2)=(e-1)(x-1)=(e-1)x-e+1
y=(e-1)x-e+1+e-2
=(e-1)x-1