( a , b ) = 7 -> a = 7x /
/ x , y ∈ N*
( a , b ) = 7 -> b= 7y /
a × b = 294 ( inlocuim ) -> 7x × 7y = 294
49 xy = 294
xy = 294 / 49
xy = 6
xy = 6 -> ( x , y ) ∈ { ( 1 , 6 ) ; ( 6 , 1 ) ; ( 3 , 2 ) ; ( 2 , 3) }
---> ( a , b ) ∈ { ( 42 , 7 ) ; ( 7 , 42 ) ; ( 21 , 14 ) , ( 14 , 21 ) }