19.(2023春•湖北期末)已知函数f(x)=alnx−x+1(a∈R)f(x)=alnx-x+1(a\in R)f(x)=alnx−x+1(a∈R).(1)讨论f(x)f(x)f(x)的单调区间;(2)若曲线f(x)f(x)f(x)在x=3x=3x=3处的切线方程为y=−13x+2ln3−1y=-\frac{1}{3}x+2ln3-1y=−31x+2ln3−1.(ⅰ)求实数aaa的值;(ⅱ)关于xxx的不等式f(x)⩽k(x−1)f(x)\leqslant k(x-1)f(x)⩽k(x−1)对任意的x>0x>0x>0恒成立,求正实数kkk的值.