What is the identity 20 and what is the identity

The identity is that under certain conditions, the left and right sides of the equal sign are always equal.

For example, 2 = 2 is equal under any condition, then this is an identity (a certain condition here is under any condition).

For example, if a * 1 a = 1 is constant when a is not equal to 0, then the condition here is that a is not equal to 0

Replace the algebraic formula in the equation with its eligible identity, and wait until the equation. This is the basis of algebraic identity transformations.

Mathematically, an identity is an equation that always holds no matter how its variables are valued.

For example: x -y = (x-y)x(x+y).

Identity Mathematically, an identity is an equation that always holds no matter how its variables are valued. The identity symbol " " is a relationship between two analytic formulas. Given two analytic formulas, they are said to be identical if they have equal values for any number or array of the common part (or a subset of the common part) of their defined domain (see function).

For example, x 2 y 2 and (x y) (x y) have a 2 b 2 (a b) (a b) (a b) for any set of real numbers (a, b), so x 2 y 2 is the same as ( x y) (x y) . The identity of two analytic expressions cannot be discussed in isolation from the specified set of numbers, because the same two analytic expressions may be identical in one set and non-constant in the other. For example, with x, it is constant within the set of non-negative real numbers, while it is not constant within the set of real numbers.

The identity symbol " ".

An identity is a mathematical formula in which the two sides of an equal sign are always equal, regardless of the value of its variables. The equal sign in an identity can be represented by an identity sign ( ). a^2-b^2=(a+b)(a-b) a^2-2ab+b^2=(a-b)^2 a^2+2ab+b^2=(a+b)^2

Reference: wiki

Equations can be divided into three categories: Identity: The letters in the algebra on both sides of the equal sign can make the values of the algebra on both sides of the equal sign equal no matter what kind of value they take, such an equation is called an identity For example, 2 3 5, a a 2a, (x y) (x y) x2 y2, etc., are all identities conditional equations:

The letters in the algebra on both sides of the equal sign can only make the values of the algebra on both sides of the equal sign equal when certain values are taken, such an equation is called a conditional equation For example, 2x 6, the values on both sides of the equal sign can be equal only if x 3; x2 7 x 3 3, only when x 0 or x 7 The values on both sides of the equal sign can be equal, so they are conditional equations Contradictory equations: formulas that are connected by equal signs in form, but cannot be true in substance, or within the range of the specified number, the values taken by the literal symbol cannot be found to make the values on both sides of the equal sign equal Such an equation is called a contradictory equation For example, a 1 a 2 is a contradictory equation

You can also use a simpler example: x + x 2x is the meaning of identity.

Identities, a mathematical concept, is an equation that always holds no matter how its variables are valued. The scope in which the identity holds is the common part of the domain of the left and right functions, but the two independent functions have their own domains, which are constant with x in the set of non-negative real numbers, but not in the set of real numbers.

If there are multiple variables in an identity, there is also a variable, and if there is one variable on both sides of the identity, the identity is a relationship between two analytic expressions. It ** is based on e ix=cosx+isinx (trigonometric representation of complex numbers), so that x= gives e i + 1 = 0.