Root of a function

Alternate uses: see Root (disambiguation).

In mathematics, root of a function f is a number x that turns the value of f to 0:

f(x) = 0.

One can say about polynomial roots, because a polynomial is also a function. There exists a theorem that states that every polynomial with complex coefficients has at least one (complex) root, and from this and the polynomial remainder theorem it can be concluded that every complex polynomial of degree n has exactly n complex roots (some of them may be equal).