Diophantus was a
mathematician
from
Alexandria in ancient
Greece. He lived sometime
around 250 AD but giving exact dates
is extremely difficult. No-one
really knows for sure.
Diophantus was interested in solving polynomial
equations with integer or rational equations.
We now call these Diophantine equations.
The most famous Diophantine equation of them all is
xn+yn=zn
and Fermat's notorious marginal note
I have discovered a truly remarkable proof which this margin is too small to contain
was written in his copy of Diophantus'
Arithmetica.
See also the proof of Diophantus' theorem on Pythagorean triples
and Fermat's Last Theorem.