Question

Determinati nr prime x si y, stiind ca:
a) x+y=39
b) x-y=95

Answer 1

$a)~x+y=39=impar \Rightarrow x~si~y~au~paritati~diferite \Rightarrow \\ \\ unul~dintre~numere~este~2~(deoarece~2~este~singurul~numar~prim \\ \\ par) \Rightarrow al~doilea~numar~este~39-2=37.~ \\ \\ Solutie:~(x,y) \in \{(2,37);(37,2 \}..$

$b)~x-y=95=impar \Rightarrow x~si~y~au~paritati~diferite \Rightarrow y=2 \Rightarrow \\ \\ \Rightarrow x=95+2=97. \\ \\ Solutie:~x=97,~y=2.$