Question

Реши систему неравенств  −x+9>0
{
3x<−12

 

x∈(−∞; ...).

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Answer 1

$\left \{ {{-x+9>0} \atop {3x<-12\ \ \ |:3}} \right. \\\\\left \{ {{-x>-9\ \ \ |:(-1)} \atop {x<-4}} \right. \\\\\left \{ {{x<9 \atop {x<-4}} \right. \\\\x<-4\\\\x\in (-\infty;-4)$