Complex Numbers

A complex number, in mathematics, is a number comprising a real number and an imaginary number. It can be written in the form a + bi, where a and b are real numbers, and i is the standard imaginary unit with the property i ² = −1. The complex numbers contain the ordinary real numbers, but extend them by adding in extra numbers and correspondingly expanding the understanding of addition and multiplication. This is in order to form a closed field, where any polynomial equation has a root, including examples such as x² = −1.