Răspuns :
[tex]a-84\ \textless \ 1 \\ a\ \textless \ 1+84 \\ a\ \textless \ 85 [/tex]
x apartine (-infinit, 85)
[tex]a+89\ \textless \ 91 \\ a\ \textless \ 91-89 \\ a\ \textless \ 2 [/tex]
x apartine (-infinit, 2)
x apartine (-infinit, 85)
[tex]a+89\ \textless \ 91 \\ a\ \textless \ 91-89 \\ a\ \textless \ 2 [/tex]
x apartine (-infinit, 2)