Question

помогите с 4-мя заданиями

Answer 1

$\displaystyle\\a)\left \{ {{-2x > 2} \atop {-x < -8}} \right. \left \{ {{x < -1} \atop {x > 8}} \right. \\\\x\in\varnothing\\\\b)\left \{ {{-\frac{2}{7}x > \frac{3}{8} } \atop {x\geq -5}} \right. \left \{ {{x < -\frac{21}{16} } \atop {x\geq -5}} \right. \\\\x\in[-5;-\frac{21}{16} )$

$\displaystyle\\d)\left \{ {{-\frac{2}{9} x\leq -2} \atop {-x < -\frac{2}{3} }} \right. \left \{ {{x\geq 9} \atop {x > \frac{2}{3} }} \right. \\\\x\in[9;\infty)\\\\e\left \{ {{-\frac{1}{3} x < -2} \atop {-\frac{4}{5} x > \frac{2}{7} }} \right. \left \{ {{x > 6} \atop {x < -\frac{5}{14} }} \right. \\\\x\in\varnothing$

Answer 2

$\displaystyle\bf\\1)\\\\\left \{ {{-2x > 2} \atop {-x < -8}} \right. \ \ \Rightarrow \ \ \left \{ {{x < -1} \atop {x > 8}} \right. \ \ \Rightarrow \ \ x\in \oslash\\\\2)\\\\\left \{ {{-\dfrac{2}{7}x > \dfrac{3}{8} } \atop {x\geq -5}} \right. \ \ \Rightarrow \ \ \left \{ {{x < -1,3125} \atop {x\geq -5}} \right. \ \ \Rightarrow \ \ x\in\Big[-5 \ ; \ -1,3125\Big)\\\\3)$

$\displaystyle\bf\\\left \{ {{-\dfrac{2}{9} x\leq -2} \atop {-x < -\dfrac{2}{3} }} \right. \ \ \Rightarrow \ \ \left \{ {{x\geq 9} \atop {x > \dfrac{2}{3} }} \right. \ \ \Rightarrow \ \ x\in\Big[9 \ ; \ +\infty\Big)\\\\4)\\\\\left \{ {{-\dfrac{1}{3} x < -2} \atop {-\dfrac{4}{5} x > \dfrac{2}{7} }} \right. \ \Rightarrow \ \ \ \left \{ {{x > 6} \atop {x < -\dfrac{5}{14} }} \right. \ \ \Rightarrow \ \ x\in \oslash$