Question

cardinalul multimii A= { x∈N | 7 supra 19 mai mic x supra 19 mai mic 13 supra 19 } este ...

Answer 1

$\frac{7}{19}< \frac{x}{19}<\frac{13}{19} \\ \\ 7 < x<13 \\ \\ x \ apartine \ N \\ \\ \boxed{x=(8;9;10;11;12)}$

Answer 2

$\frac{7}{19} < \frac{x}{19} < \frac{13}{19} \\ 7<x<13\\ x\in\{8,9,10,11,12\}\\ cardinal(A)=5$