Respuesta :

evgeniylevi
Try this solution:
1. according to the condition
[tex] \left \{ {{x \geq 0} \atop {20+x\ \textgreater \ 0}} \right. \ =\ \textgreater \ \ x \geq 0.[/tex]
2. for more details see the attached graph.

Answer: [0;+oo)
Ver imagen evgeniylevi