Complex Numbers
A complex number is a combination of a real number and an imaginary number, which can be expressed in the form of a + bi where a is the real number and b is the imaginary number. If a = 0 the number is purely imaginary; if b = 0 the number is purely real. The FTA needs complex numbers because a real number is a complex number with an imaginary number that equals to zero (b = 0).
