Beyoncé debuted "1+1," a stark, romantic ballad from her upcoming album 4, on last night's season finale of American Idol. The song, co-written by The-Dream and Tricky Stewart, faintly echoes the sound of Prince's classic showstopper "Purple Rain," but swaps out arena rock grandeur for a more intimate arrangement focused on her magnificent voice. It may not be an obvious hit, but it was a smart decision to showcase the song on a singing competition like Idol.

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