polynomial equation

a much more rigorous work can be found here:

http://www-history.mcs.st-and.ac.uk/HistTopics/Fund_theorem_of_algebra.html

applying simple logic that polynomial of degree two has two roots similarly polynomial of n degree has n no; of roots use brain it will simple crack iit

If you find it in a text book, let me assure you, that textbook isnt elementary!