\[\begin{array}{l} 1 \le \frac{{13 - 2z}}{z} \le \frac{3}{2} \Leftrightarrow \left\{ \begin{array}{l} \frac{{13 - 2z}}{z} - 1 \ge 0\\ \frac{{13 - 2z}}{z} - \frac{3}{2} \le 0 \end{array} \right.\\ \Leftrightarrow \left\{ \begin{array}{l} \frac{{13 - 2z - z}}{z} \ge 0\\ \frac{{26 - 4z - 3z}}{{2z}} \le 0 \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} \frac{{13 - 3z}}{z} \ge 0\\ \frac{{26 - 7z}}{{2z}} \le 0 \end{array} \right.\\ \Leftrightarrow \left\{ \begin{array}{l} \left[ \begin{array}{l} \left\{ \begin{array}{l} 13 - 3z \ge 0\\ z > 0 \end{array} \right.\\ \left\{ \begin{array}{l} 13 - 3z \le 0\\ z < 0 \end{array} \right. \end{array} \right.\\ \left[ \begin{array}{l} \left\{ \begin{array}{l} 26 - 7z \ge 0\\ 2z < 0 \end{array} \right.\\ \left\{ \begin{array}{l} 26 - 7z \le 0\\ 2z > 0 \end{array} \right. \end{array} \right. \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} \left[ \begin{array}{l} \left\{ \begin{array}{l} z \le \frac{{13}}{2}\\ z > 0 \end{array} \right.\\ \left\{ \begin{array}{l} z \ge \frac{{13}}{3}\\ z < 0 \end{array} \right. \end{array} \right.\\ \left[ \begin{array}{l} \left\{ \begin{array}{l} z \le \frac{{26}}{7}\\ z < 0 \end{array} \right.\\ \left\{ \begin{array}{l} z \ge \frac{{26}}{7}\\ z > 0 \end{array} \right. \end{array} \right. \end{array} \right. \Leftrightarrow \left\{ \begin{array}{l} 0 < z \le \frac{{13}}{3}\\ \left[ \begin{array}{l} z < 0\\ z > \frac{{26}}{7} \end{array} \right. \end{array} \right.\\ \Leftrightarrow \frac{{26}}{7} < z \le \frac{{13}}{3} \Leftrightarrow 3,71 < z \le 4,3. \end{array}\]

Đáp án:

Giải thích các bước giải:

Ca(NO3)2→Ca2++2NO−3(NH4)2SO4→2NH4++SO42−FeSO4→Fe2++SO42−HClO⇆H++ClO−NH4NO3→NH+4+NO−3Na3PO4→3Na++PO3−4Al2(SO4)3→2Al3++3SO2−4CH3COOK→CH3COO−+K+(HCOO)2Ca→2HCOO−+Ca2+HBr→H++Br−H3PO4⇆H++H2PO−4H2PO−4⇆H++HPO2−4HPO2−4⇄H+PO3−4