The Complex Numbers
The polynomial x2 + 1 does not have any roots within the set of real numbers. A new number, called i, is introduced as a root of that polynomial. The complex numbers are all the numbers of the form a + bi where a and b are real numbers. It is a remarkable fact that every polynomial with real coefficients (or even with complex coefficients) that is not a constant function has a root within the set of complex numbers. In this chapter, we develop the basic properties of the complex numbers.