Were Napoleon and Évariste Galois alive at the same time?
Yes. Napoleon and Évariste Galois were alive at the same time for 9 years, from 1811 to 1821.
Napoleon was 42 when Évariste Galois was born.
Évariste Galois was 9 when Napoleon died, aged 51.
Napoleon
French military leader, French Emperor 1804–1814 and again in 1815
Born 15 August 1769 · died 5 May 1821, aged 51