This formula is derived by collocation method, and it can be used to solve the root of a quadratic equation with one variable. If b 2-4ac \ gt0, the equation has two unequal real roots; If b 2-4ac = 0, the equation has multiple roots; If b 2-4ac \ lt0, the equation has no real root, but has two * * * yoke complex roots.
It should be noted that this formula is only applicable to quadratic equations with one variable. If the degree of the equation is not quadratic, or the equation contains other unknowns, then this formula is no longer applicable.
Function, a mathematical term. Its definition is usually divided into traditional definition and modern definition. The essence of these two functional definitions is the same, but the starting point of narrative concept is different. The traditional definition is from the perspective of movement change, and the modern definition is from the perspective of set and mapping.
The modern definition of a function is to give a number set A, assume that the element in it is X, apply the corresponding rule F to the element X in A, and record it as f(x) to get another number set B, assume that the element in B is Y, and the equivalent relationship between Y and X can be expressed as y=f(x). The concept of function consists of three elements: domain A, domain B and corresponding rule F..
Among them, the core is the corresponding rule F, which is the essential feature of the functional relationship. [1] This function was originally translated by China mathematician Li in his book Algebra. He translated this way because "whoever believes in this variable is the function of that variable", that is, the function means that one quantity changes with another quantity, or that one quantity contains another quantity.
Understand that a function is a correspondence between sets. Then, we should understand that there is more than one functional relationship between A and B, and finally, we should focus on understanding the three elements of the function.