1)
This was two years after Aviyam became king. Why did verse 2 say that he ruled for three years?
1.
Rashi: Aviyam's third year is counted towards Asa's reign, and also towards Aviyam's reign, so Avyam reigned three years.
2.
Radak: I mentioned above (verse 1) that Rechav'am ruled for part of Yaravam's 18th year (and he died, and Aviyam became king immediately). That year was counted towards Aviyam's reign, so he reigned three years.
