They solve quadratic equations by using the method of completing the square.

Begins replacing mathematical statements with symbols.

Replaced unknown values with letters.

discovered how to solve system of equations.

Writes about the first explanation on solving equations and why we do the same operation on both sides.

Gave the solutions to quadratic equations and cubic equations.

Write the book, Elements of Algebra

Proved the Fundamental Theorem of Algebra

Makes discovery on noncommutative algebra.