(2022•山东)已知a>0且a≠1,若函数\( f\left(x\right)=\left\{\begin{array}{c}\left(a-1\right)x+5,xϵ(-\infty ,2)\\ {a}^{x},xϵ[2,+\infty )\end{array}\right.​\)在(\( -\mathrm{\infty },+\mathrm{\infty }​\))上具有单调性,则实数a的取值范围是______.