5.6 - The Fundamental Theorem of Algebra

To use the Fundamental Theorem of Algebra to solve polynomial equations with complex solutions

Last time we worked on factoring polynomial equations to find their solutions. You may have wondered, how did we know when to stop factoring? Like, is there a way to know exactly how many factors a polynomial has, so we can know if we have identified all of them?

In Algebra I, we learned three cases for the number of real-number solutions to a quadratic equation:

But in Algebra II, when we factored the quadratics we saw that each related equation has two roots:

We already know that a first-degree (linear) polynomial has one zero, the x-intercept. This suggests that the number of roots of a polynomial is related to its degree.