[tex]\it 7)\ \dfrac{18}{x+3} =ireductibil\breve a\ dac\breve a\ num\breve ar\breve atorul\ \c si\ numitorul\ sunt\ prime\ \^ intre\ ele[/tex]
[tex]\it x=2\ \Longrightarrow\ \dfrac{18}{2+3 }=\dfrac{18}{5}=\ ireductibil\breve a[/tex]
