How do you find the complex roots of #x+8=0#?
This equation has one real (complex) root, namely
This is a polynomial equation of degree
We can subtract
#x = -8#
This is the only root.
The Fundamental Theorem of Algebra (FTOA) tells us that any non-constant polynomial has a zero in the Complex numbers.
A straightforward corollary of the FTOA, often stated with it, is that a polynomial of degree
So a linear equation has exactly one root, a quadratic equation has two, a cubic has three, etc.