Odpowiedź:
1. [tex]\frac{3x - 15}{x + 2}[/tex] =
= [tex]\left \{ {{3x-15\leq 0} \atop {x+2>0}} \right. \\\left \{ {{3x-15\geq 0} \atop {x+2<0}} \right.[/tex] =
=[tex]\left \{ {{x\leq 5} \atop {x>-2}} \right. \\\left \{ {{x\geq 0} \atop {x<-2}} \right.[/tex]
2. [tex]\frac{x-4}{2x-6} \leq -4[/tex] =
= [tex]\frac{x-4}{2x-6} +44\leq 0[/tex] = [tex]\frac{x-4 +4(2x-6)}{2x-6} \leq 0[/tex] =
= [tex]\frac{x-4+8x-24}{2(x-3)} \leq 0[/tex] = [tex]\frac{9x - 28}{2(x-3)} \leq 0[/tex] =
= [tex]\left \{ {{9x-28\leq 0} \atop {2(x-3)> 0}} \right. \\\left \{ {{9x-28\geq 0} \atop {2(x-3)<0}} \right.[/tex] = [tex]\left \{ {{x\leq \frac{28}{9} } \atop {x>3}} \right. \\\left \{ {{x\geq \frac{28}{9} } \atop {x<3}} \right.[/tex]
