Évariste ___, 19th-century French math prodigy for whom a differential theory is named

GALOIS

This tragic genius solved quintic equations at 20 before dying in a duel the next year.

This clue points to Évariste Galois, a brilliant French mathematician from the early 1800s who made groundbreaking contributions to algebra before dying at just 20. The "differential theory" hint refers to Galois theory, his revolutionary work connecting group theory and polynomial equations. The blank in the clue is filled by his last name, "Galois," which fits both the letter count and the historical context. No wordplay here—just a direct reference to a famous figure in math history.