1765-1822

Italian mathematician and physician who was the first to prove that quintic equations (equations in which one term is raised to the fifth power) cannot be solved using only radicals (square roots). This important proof, which flew in the face of accepted mathematical thinking, was not well received by mathematicians of the day; with the exception of Augustin Cauchy, on whom it had a tremendous impact. In developing his proof, Ruffini also laid the foundations for modern group theory, which did not then exist.