Задание 48

а) $\{\begin{array}{c}\hfill x-2>0\\ \hfill -2x+7\ge 0\end{array}\iff \{\begin{array}{c}\hfill x>2\\ \hfill x\ge 3.5\end{array}\iff x\in (2;3.5]$

б)$[\begin{array}{c}\hfill \frac{2x-3.5}{5}<\frac{1-4x}{2}\\ \hfill 12-5x>x\end{array}\iff$ $[\begin{array}{c}\hfill 4x-7<5-20x\\ \hfill 12>6x\end{array}$ $\iff$ $[\begin{array}{c}\hfill 24x<12\\ \hfill 12>6x\end{array}$ $\iff [\begin{array}{c}\hfill x<0.5\\ \hfill x<2\end{array}$ $\iff x\in (-\infty ;2)$