Question

Срочноооо! Пожалуйста (

Answer 1

$\{ {{-3x>x-4(3x+1) } \atop {20-x>(1+9x)^{2}-81x^{2} }} \right. \longrightarrow \{ {{-3x>x-12x-4 } \atop {20-x>1+18x+81x^{2} -81x^{2} }} \longrightarrow \{ {{x>-\frac{1}{2} } \atop {x<1} }} \\x \in (-0,5; 1)$