Complex multiplication rule: two complex numbers are multiplied, similar to two polynomials. In the result, i2=- 1, and the real part and imaginary part are merged respectively. The product of two complex numbers is still a complex number. The earliest literature about the roots of complex numbers comes from Helen, a Greek mathematician in the 1 th century. She thinks that a flat-topped pyramid is impossible.

Complex number:

We call a number in the form of z = a+bi (both a and b are real numbers) a complex number. Where a is called the real part, b is called the imaginary part, and I is called the imaginary part. When the imaginary part b of z = 0, then z is a real number; When the imaginary part of z. When b≠0 and the real part A = 0, Z is often called pure imaginary number. Complex number field is an algebraic closure of real number field, that is, any polynomial with complex coefficients always has roots in complex number field. Complex number was first put forward by Italian Milan scholar Cardan in16th century, and this concept was gradually accepted by mathematicians.