The list of artists set to perform at the 2015 Billboard Music Awards continues to grow with the addition of Mariah Carey, Billboard announced Tuesday. The 14-time Billboard Music Award winner hasn't performed at the show since 1998. Carey, who dropped her new single, "Infinity," on April 26, plans to release a compilation of her No. 1 hits on May 18. Her Las Vegas residency begins May 6 at The Colosseum at Caesars Palace.