Earliest methods used to solve quadratic equations were geometric. Babylonian cuneiform tablets from around 1800-1600 BCE contain problems that can be reduced to solving quadratic equations, showing they understood techniques. The Egyptians also solved quadratic equations geometrically in the Middle Kingdom around 2050-1650 BCE. Later mathematicians like Euclid, Brahmagupta, and al-Khwārizmī developed more algebraic methods, with Brahmagupta explicitly describing the quadratic formula around 628 AD. The need for convenience ultimately led to the discovery of the general quadratic formula, first obtained by Simon Stevin in 1594 and published by René Descartes in 1637 in the modern form still used today.