Analysis I (part 2) : Introduction to complex numbers

The equation z^2=-1 has no solution in R. We introduce the system of complex numbers C: this is a body that contains R and allows us to solve this equation. First, we introduce different ways of representing a complex number. We then discuss the solutions of equations of the form zn=w with n∈N∗ and w∈C . We conclude with a more general theorem about roots of polynomials: the fundamental theorem of algebra . This chapter is independent of the rest of the course; in the following, we will almost always consider real numbers and not complex numbers.