Who discovered or made quadratic inequalities?

The quadratic formula was made by Muhammad al-khwarizmi.

A quadratic inequality is a function whose degree is 2 and where the y is not always exactly equal to the function. Al Khwarzmi created the quadratic equation but Pythagoras and Euclid created a general procedure to find solutions of the quadratic equation. The Greek mathematician Diophantus solved the quadratic equation in his work Arithmetica,  but giving only one root, even when both roots were positive.