In mathematics, I is an imaginary unit, which can refer to an unreal number or a number that does not represent a specific number. The imaginary number is a number in the form of a+b*i, where a and b are real numbers, and b≠0, i? =- 1。 The real part A of the imaginary number a+b*i can correspond to the horizontal axis on the plane, 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 people use the term pure imaginary number to represent the so-called imaginary number, and imaginary number refers to any complex number whose imaginary part is not zero. In mathematics, even numbers whose exponents are negative are defined as pure imaginary numbers. All imaginary numbers are complex numbers. Defined as me? =- 1。 But the imaginary number has no arithmetic root, so √ (-1) = i. For z=a+bi, it can also be expressed in the form of iA power of e, where e is constant, I is imaginary unit, and A is imaginary amplitude, which can be expressed as z=cosA+isinA.