ותלך לדרוש את ה
Rashi comments that she went to Shem and Ever. The question can be asked why didn't she ask her husband Yitzchak or Avraham who was still alive? Also, once she got the amswer why didn't she tell Yitzchak. After all, she was told that רב יעבוד צעיר, and that when one was up the other would be down. if she had told Yitzchak, it probably would have changed his views on the Berachos.