جواب
farz konid (a,b) = d . darim a = da` va b = db` ke (a`,b`) = 1. va tebghe farz darim (a,b,c) = (d,c) = 1
.(`hal tebghe sooorate soal darim ab = c(a-b) ==> d2 * a` * b` = d * c * (a`-b`) ==> d * a` * b` = c (a`-b
d | c(a` - b`) . chon (d,c) = 1 pas darim d | a` - b` . az tarafi chon (...