The Fundamental Theorem of Algebra
The Fundamental Theorem of Algebra states that every polynomial equation of degree \(n\) with complex number coefficients has \(n\) roots, or solutions, in the complex numbers.

The Fundamental Theorem of Algebra is an example of an ‘existence’ theorem in mathematics, like the Intermediate Value Theorem. This theorem guarantees the existence of at least one zero but gives us no algorithm to find it.
A step-by-step guide to the fundamental theorem of algebra
Every polynomial function contains at least one complex zero, according to the Fundamental Theorem of Algebra. The cornerstone for solving polynomial equations is this theorem.
There is at least one complex root in every polynomial equation with complex coefficients and degrees. Gauss was the first to prove this theorem. It’s the same as saying that a polynomial \(P(z)\) of degree \(n\) has \(n\) values \(z_i\) (some of them possibly degenerate) for which \(P(z_i)=0\). Polynomial roots are the names given to such numbers.
An example of a polynomial with a single root of multiplicity \(>1\) is \(z^2-2z+1=(z-1)(z-1)\) which has \(z=1\) as a root of multiplicity \(2\).
The Fundamental Theorem of Algebra – Example 1:
what are the roots of \(x^2-4\)?
\(x^2-4\) has a degree of \(2\) (the largest exponent of \(x\) is \(2\)), so there are 2 roots.
Let us solve it. We want it to be equal to zero:
\(x^2-4=0\)
\(x^2=4\)
Now, take the square root of both sides:
\(x=\pm2\)
So, the roots are \(+2\) and \(-2\).
Exercises for the Fundamental Theorem of Algebra
- Write the polynomial that has the following roots \(4\) (with multiplicity \(3\)), \(2\) (with multiplicity \(2\)) and \(0\).
- Find the zeroes of the polynomial \(x^2+3x+2\).
- Find the zeroes of the polynomial \(x^3-4x^2-4x+16\).
- How many roots does the following equation have? \(\left(2x^2+2x-1\right)\left(3x^2-9\right)=0\)

- \(\color{blue}{f(x)=(x-4)^3(x-2)^2 x}\)
- \(\color{blue}{x=-1, \:or\: x=-2}\)
- \(\color{blue}{x=2, x=-2 \:or\: x=4}\)
- \(\color{blue}{4}\)
Related to This Article
More math articles
- How to Use Area Models to Multiply One-Digit Numbers By Up to 4-digit Numbers
- Top 10 TABE Prep Books (Our 2023 Favorite Picks)
- Geometry Puzzle – Challenge 66
- How to Find the Center and the Radius of Circles? (+FREE Worksheet!)
- Descending into Numbers: A Deep Dive into the Floor Value
- Top 10 TSI Math Practice Questions
- How to Manage Your Time Effectively on the GED Math Test?
- How to Calculate the Area, Perimeter, and Radius of Quarter Circles
- Identify 3–Dimensional Figures
- How to Find Length of a Vector
What people say about "The Fundamental Theorem of Algebra - Effortless Math: We Help Students Learn to LOVE Mathematics"?
No one replied yet.