In mathematics, imaginary numbers are numbers in the form of a+b*i, where a and b are real numbers, b≠0, and i =- 1. 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.
brief introduction
When the imaginary number intrudes into the field of numbers, people know nothing about its practical use, and there seems to be no quantity expressed by complex numbers in real life, so people have all kinds of doubts and misunderstandings about it for a long time. Descartes called it "imaginary number" because it is false; Leibniz thinks: "imaginary number is a wonderful and strange hiding place for gods." It is almost an amphibian that exists and does not exist. "
Although Euler used imaginary numbers in many places, he said, "All mathematical expressions in the form of √- 1 and √-2 are impossible, imaginary numbers, because they represent the square root of negative numbers. For such figures, we can only assert that they are neither nothing nor more than nothing, nor less than nothing. They are purely illusory. "