While the Septuagint was a collection of the books of the
Old Testament and an attempt at a canon, it was
not a fixed
in the first century
. It was a popular translation of
scripture because Greek was the common language of the
entire Mediterranean world by the time of the Apostolic Church.
It is not surprising that this is
the translation--and canon--used
by Christ and the New Testament writers: 300 of 350
quotations from the Old Testament in the New Testament
are from the Septuagint.
The remainder are often
paraphrases of either the Hebrew or the Greek only.