Last time we showed that given (integers) with
, there are
with
such that
. We began today by showing that these integers
are unique. When
, we say that
divides
, in symbols
.
Definition. A greatest common divisor of the integers not both zero, is a positive integer
that divides both
and such that any integer that divides both
, also divides
.
We showed that for any not both zero, there is a unique such
, in symbols
or simply
. We also showed the following characterization:
Theorem. Let
be integers, not both zero. Let
for some integers
,
. Then the following are equivalent statements about the integer
:
.
,
, and
.
.
is the least member of
.