Around 2000 BC, a quadratic equation of one yuan appeared on the clay tablets of Babylon and its solution: it is known that the sum of a number and its reciprocal is equal to a given number, and the calculation method of this number is X 1+X2 = B, X 1 X2 = 1, X 2-BX+65438+. It can be seen that the Babylonians already knew the formula for finding the root of the quadratic equation of one variable. But they didn't accept negative numbers at that time, so they omitted negative roots. Egyptian papyrus literature also involves the simplest quadratic equation, for example, AX 2 = B. In the 4th and 5th centuries BC, China had mastered the formula for finding the root of a quadratic equation. Diophantine (246-330) in Greece only takes the positive root of a quadratic equation, even if both of them are positive roots, he only takes one of them. In 628 AD, a formula for finding the root of quadratic equation x 2+px+q = 0 was obtained from the Yarlung Zangbo River Correction System written by India. In Algebra written by Al-Hualazimi of Arabia, the solutions of equations are discussed, and the first and second equations are solved, involving six different forms, so that A, B and C are positive numbers, such as AX 2 = Bx, AX 2 = C, AX2+C = Bx, AX2+Bx = C, AX. It is in line with Diophantine's practice to discuss quadratic equations in different forms. In addition to several special solutions of quadratic equation, Al-Hualazimi also gave the general solution of quadratic equation for the first time, admitting that the equation has two roots and irrational roots, but he doesn't know the imaginary root. /kloc-in the 6th century, Italian mathematicians began to understand cubic equations with complex roots. David (1540- 1603) not only knows that the unary equation always has a solution in the range of complex numbers, but also gives the relationship between roots and coefficients. Chapter 9 Arithmetic China Pythagorean Theorem No.20, finding the positive root is equivalent to x 2+34x-7 1000 = 0. China mathematicians also applied interpolation in the study of equations.