Răspuns:
6
Explicație pas cu pas:
[tex]-\frac{x}{2} >-\frac{20}{x}>-\frac{x}{1,7} |*(-1)\\\frac{x}{2} <\frac{20}{x}<\frac{x}{1,7},~\left \{ {{x^{2}<2*20} \atop {20*1,7<x^{2}}} \right.~\left \{ {{x^{2}<40} \atop {x^{2}>34}} \right.\\[/tex]
Deoaece x∈N si 34<x²<40, ⇒x=6
