Răspuns :
p/q ireductibila
1 -p/q=q/q -p/q=(q-p)/q
Fie q-p=k, k€|N*
=>k+p=q si p=q-k
Deci (q-p)/q=k/q
Presupunem ca exista d a.i.
d|q si d|k
=> d|(q-k) => d|p ( q-k = p )
Dar (p, q)=1
=> d=1 => (q, k)=1
=> k/q ireductibila
=> (1 -p/q) ireductibila
1 -p/q=q/q -p/q=(q-p)/q
Fie q-p=k, k€|N*
=>k+p=q si p=q-k
Deci (q-p)/q=k/q
Presupunem ca exista d a.i.
d|q si d|k
=> d|(q-k) => d|p ( q-k = p )
Dar (p, q)=1
=> d=1 => (q, k)=1
=> k/q ireductibila
=> (1 -p/q) ireductibila