Question

Aflatin x,y sttind ca 49 pe 7x+2y este echiunitara si x+y este maxim...

Answer 1

49/7x+2y⇒fractie echiunitara;
⇒7x+2y=49
⇒x=5⇒y=7;
⇒7·5+2·7=35+14=49;
⇒x+y=5+7=12;
⇒x=3⇒y=14;
⇒7·3+2·14=21+28=49;
⇒x=1⇒y=21;
⇒7+42=49;
⇒din cele trei solutii ,ne convine ultima ,deoarece x+y-maxim ,unde x+y=1+21=22;⇒22>3+14=17;⇒22>5+7=12;

Answer 2

7x+2y=49
7}7x, 7|49 =>7|2y=> 7|y si 2y<49=> y<24
$y\in \{7,14,21\} \\ y=7=\ \textgreater \ x=5=\ \textgreater \ x+y=12 \\ y=14=\ \textgreater \ x=3 \\ x+y=17 \\ y=21=\ \textgreater \ x=1 \\ x+y=22$
Deci x=1 si y=21