1.(2022•齐齐哈尔二模)已知数列{an}\{a_{n}\}{an}的通项公式an=n2−9n+kn,a4a_{n}=n^{2}-9n+\frac{k}{n},{a_4}an=n2−9n+nk,a4是数列{an}\{a_{n}\}{an}的最小项,则实数kkk的取值范围是((( )))