Ta có : Ư ( 5 ) = { + 1 ; + 5 )
TH1 :
2x + 1 = - 1 => x = - 1
y - 1 = - 5 => y = - 4
TH2 :
2x + 1 = - 5 => x = - 3
y - 1 = - 1 => y = 0
TH3 :
2x + 1 = 1 => x = 0
y - 1 = 5 => y = 6
TH4 :
2x + 1 = 5 => x = 2
y - 1 = 1 => y = 2
Vậy ( x;y ) \(\in\) { ( - 1 ; - 4 ) ; ( - 3 ; 0 ) ; ( 0 ; 6 ) ; ( 2 ; 2 ) }