Răspuns :
[tex]x+y=5\Rightarrow x=5-y\\
x\cdot y=6\\
(5-y)\cdot y=6\\
5y-y^2=6\\
5y-y^2-6=0\\
y^2-5y+6=0\\
\Delta=25-24=1\\
y_1=\frac{5+1}{2}=3\\
y_2=\frac{5-1}{2}=2\\
Pentru\ y=3\Rightarrow x=2\\
Pentru\ y=2 \Rightarrow x=3\\
S:(x,y)\in \{(3,2);(2,3)\}[/tex]