The Fundamental Theorem of Algebra states for a n-degree equation, there are n roots, real or imaginary. Repeated roots are counted. This means there are 2 roots in a quadratic equation, 3 in a cubic, 4 in a quartic and so on.
For instance, \(x^2=4\)
The equation is quadratic, and thus there are 2 roots.
The root \(0\) is repeated \(4\) times, since the equation is quartic.
You are also welcome to prove this below.