Linked from
The 41 pages that link to Fundamental theorem of algebra, each with the reason it gives.
Algebraic numberRelated: It establishes the complex setting in which algebraic numbers are defined.
Cubic equationRelated: It guarantees three complex roots for every cubic, counting multiplicity.
Zero of a functionRelated: It guarantees that complex zeros exist for every nonconstant polynomial.
Marden's theoremRelated: It guarantees a cubic's three roots when multiplicities are counted.