Complex Numbers

Complex numbers are the numbers with the format a + b i, where a and b are real numbers and
i ² = - 1. If we denote the set of complex numbers by C, then

C = { a + b i , where a and b are real numbers, i² = -1 }

If in the number x = a + b i , b is set to zero, then x = a, where a is a real number. Thus, all real numbers are complex numbers, i.e., the set of complex numbers includes the set of real numbers.