An equation with algebraic expressions on both sides of an equal sign and only one unknown (unary) with the highest degree of 2 (quadratic) is called a unary quadratic equation. To judge whether an equation is a quadratic equation, it is necessary to simplify the equation to see if it meets the conditions.
Characteristics of quadratic equation with one variable
1, containing an unknown number.
2. The maximum number of unknowns is 2.
3. The univariate quadratic equation is an integral equation. To judge whether an equation is an unary quadratic equation, first look at whether it is an integral equation, and then sort it out. If it can be arranged in the form of AX2+BX+C = 0 (A ≠ 0), then this equation is a quadratic equation.
4. Turn the equation into a general form: when AX2+BX+C = 0, it should satisfy (a≠0).
history
The 5th-11century was a dark period in European history. The Catholic Church has become an absolute force in European society. The feudal religious rule made ordinary people believe in the kingdom of heaven and pursue the afterlife, which made them indifferent to secular life and uninterested in nature. The church preached the truth of the apocalypse and had absolute authority to explain this truth, which led to the repression of reason and the stagnation of European civilization throughout the Middle Ages.
Because the Romans paid attention to practicality and did not develop abstract mathematics, Europe in the dark ages finally made no achievements in the field of mathematics. During this period, Arabs made great contributions to the preservation and dissemination of Greek, Indian and even China cultures, and finally prepared academic premises for the Renaissance in modern Europe.
After the overthrow of the Umayyad dynasty, the Abbasid dynasty moved to Baghdad, and its second caliph Mansour imitated the old Persian system and established a complete administrative system.
In this book, he defined "al-jabr" as an operation, that is, moving a reduced quantity on one side of the equation to the other side of the equation to become an added quantity; The word "wa" means "and"; "al-muqābala" means to eliminate the same kind of positive terms on both sides of the equation, which is translated as "cancellation" here.