History of Algebra

Babylonians solve quadratic equations with the completing the square method.

Greek mathematician Pythagoras' followers use geometric, visual strategies to solve equations.
http://www.mathopenref.com/images/bioimages/pythagoras1.jpg

Seleucus of Seleucla discovers that tides are caused by the moon.

Greek mathematician Diophantus of Alexandria begins replacing statements with symbols.
https://lh3.googleusercontent.com/68o1Eu2-SmZqulUAg8IuccsRT0_8FwuEq_qIQHIlk25Tjjfh9B1HwxBa1PoOcqGr5d9Y=s85

Bhaskara replaces unknown quantities with letters, while Brahmagupta discovers ways to solve systems of equations in India.
http://glimpse2u.weebly.com/uploads/1/5/3/6/15369228/521745527.jpg?157
http://www.storyofmathematics.com/images2/brahmagupta.jpg

In Iraq, Muhammad Ibn Musa Al-Khwarizmi writes a book containing the first clear explanation of solving equations by doing the same operation on both sides.
http://www.yesiknowthat.com/wp-content/uploads/2012/10/Muhammad_ibn_Musa_al-Khwarizmi.jpg

Nicholas Copernicus discovers that the sun is the center of the universe.
http://cp91279.biography.com/Bio_Mini-Bios_Copernicus_SF_HD_768x432-16x9.jpg

Girolamo Cardano writes a book containing solutions to cubic and quadratic equations.
http://www.yesiknowthat.com/wp-content/uploads/2012/10/Muhammad_ibn_Musa_al-Khwarizmi.jpg

Cardano publishes a book with the solutions to the quartic equation, which was discovered by his assistant Ludovico Ferrari.

Francois Viete starts uses letters to replace variables and uses the +/- signs to represent addition and subtraction.
http://www.biografiasyvidas.com/biografia/v/fotos/viete_francois.jpg