What are they going to buy?
( x + 1) . ( y + 2) = 7
\(\Rightarrow\)( x + 1) . ( y + 2) \(\in\)Ư( 7 )
Ư(7) = 1.7 = -1 . (-7)
x + 1 | 1 | 7 | -1 | -7 |
x | 0 | 6 | -2 | -8 |
y + 2 | 7 | 1 | -7 | -1 |
y | 5 | -1 | -9 | -3 |
Vậy ( x,y) = { ( 0;5 ); ( 6;-1 ); ( -2;-9 ); ( -8; -3)