A complex number is the sum of a real number and an imaginary number, written in the form a+bi. The fundamental theorem of algebra states that if f(x) is a polynomial of degree n≥1, then f(x) has at l...A complex number is the sum of a real number and an imaginary number, written in the form a+bi. The fundamental theorem of algebra states that if f(x) is a polynomial of degree n≥1, then f(x) has at least one zero in the complex number domain. The zeros of a function f(x) are the values of x that cause f(x) to be equal to zero. The zeroes of a function f(x) are the values of x that cause f(x) to be equal to zero.