Algebraic number
In mathematics, an algebraic number is a number that is a root of a non-zero polynomial in one variable with integer (or, equivalently, rational) coefficients. For example, the golden ratio ( 1 + 5 ) / 2 {\displaystyle (1+{\sqrt {5}})/2} is an algebraic number, because it is a root of the polynomial x 2 − x − 1 {\displaystyle x^{2}-x-1} , i.e., a solution to the equation x 2 − x − 1 = 0 {\displaystyle x^{2}-x-1=0} , and the complex number 1 + i {\displaystyle 1+i} is algebraic because it is a root of the polynomial x 4 + 4 {\displaystyle x^{4}+4} .