1, the value of everything can be expressed as: a+bi, not just a real number.

We can draw an imaginary system in a plane rectangular coordinate system. If the horizontal axis represents all real numbers, then the vertical axis can represent imaginary numbers. Every point on the whole plane corresponds to a complex number, which is called a complex plane. The horizontal and vertical axes have also been renamed as real and imaginary axes. At this time, the coordinate of point p is P(a, bi). Multiply the coordinates by I, that is, the point rotates 90 degrees counterclockwise around the center of the circle.

2. Imaginary number has become the core tool for designing microchips and digital compression algorithms, and it is the theoretical basis of quantum mechanics that triggered the electronics revolution.

3. Imaginary number is an abstract concept, which is used to represent the factors that can't constitute an abstract concept in things.

The common operation formula of imaginary number and imaginary unit "I" in senior high school mathematics is: (1) I 2 =- 1.

In mathematics, imaginary numbers are numbers in the form of a+b*i, where a and b are real numbers, b≠0, i? = - 1。 The word imaginary number was founded by Descartes, a famous mathematician in the17th century, because the concept at that time thought it was a non-existent real number. Later, it was found that the real part A of the imaginary number a+b*i can correspond to the horizontal axis and the imaginary part B can correspond to the vertical axis on the plane, so that the imaginary number a+b*i can correspond to the points (a, b) on the plane.

The imaginary number bi can be added to the real number A to form a complex number in the form of a+bi, where the real numbers A and B are called the real part and imaginary part of the complex number respectively. Some authors use the term pure imaginary number to represent the so-called imaginary number, which refers to any complex number whose imaginary part is not zero.

Symbol:

1777, the Swiss mathematician Euler (or translated as Euler) began to use the symbol I to represent imaginary units. Then people organically combine imaginary numbers with real numbers and write them in the form of a+bi (A and B are both real numbers, when A equals 0, they are pure imaginary numbers, when ab is not equal to 0, they are complex numbers, and when B equals 0, they are real numbers).

In engineering operation, in order not to be confused with other symbols (such as the symbol of current), letters such as J or K are sometimes used to represent imaginary units. Usually, we use the symbol C to represent the complex set and the symbol R to represent the real set.