Rafael Bombelli (20 January 1526 (baptised) – 1572) was an Italian mathematician.
Born in Bologna, he is the author of a treatise on algebra and is a central figure in the understanding of imaginary numbers.
He was the one who finally managed to address the problem with imaginary numbers. In his 1572 book, L'Algebra, Bombelli solved equations using the method of del Ferro/Tartaglia. He introduced the rhetoric that preceded the representative symbols +i and -i and described how they both worked.
The lunar crater Bombelli is named after him.
Read more about Rafael Bombelli: Life, Bombelli's Algebra, Accomplishments, Bombelli Method