$\displaystyle \begin{array}{{>{\displaystyle}l}} -11\sqrt{x} +17+2x\leqslant 0\ \\ \rightarrow 2x-11\sqrt{x} +17\leqslant 0\ \\ \rightarrow 2x-2.\sqrt{2}\sqrt{x}\frac{11\sqrt{2}}{4} +\frac{121}{8} +\frac{15}{8} \leqslant 0\ \\ \rightarrow \ \left(\sqrt{2x} -\frac{11\sqrt{2}}{4}\right)^{2} +\frac{15}{8} \ \leqslant 0\ ( vô\ lí\ ) \ \\ Do\ đó\ không\ tồn\ tại\ x\ thõa\ mãn\ đề\ bài\ \end{array}$
