quartic equation

A quartic equation, also known as a biquadratic equation, is an algebraic equation of the fourth degree. The study of solving such equations was a significant area of focus in classical algebra, particularly in the 17th and 18th centuries. Mathematicians like Joseph-Louis Lagrange investigated why radical solutions, which worked for cubic and quartic equations, failed for equations of the fifth degree and higher. While a general radical solution for equations beyond the fourth degree was proven impossible, research continued to understand which specific higher-degree equations could be solved.1234