已知集合 $A=\left\{\overline{)x\in R}\left|x+3\right|+\left|x-4\right|\le 9\right\},B=\left\{\overline{)x\in R}x=4t+\frac{1}{t},t\in \left(0,+\infty \right)\right\}$，则集合 $A\cap B=$.