Zeros of Polynomial – Formulas, Definition With Examples

Welcome to another exciting mathematical adventure brought to you by Brighterly, the leading platform for engaging and effective learning. Today, we delve into a crucial topic in algebra that is not only foundational for further studies but also fascinating in its right — Zeros of Polynomials. As we explore this vibrant mathematical landscape, we’ll encounter towering definitions, winding formulas, and enchanting properties. Along the journey, we’ll punctuate our exploration with real-life examples, making the abstract concrete, and the theoretical practical. So, buckle up and let’s embark on this journey of discovery together!

What Are Zeros of Polynomials?

You might wonder, “what on earth are zeros of polynomials?” Don’t worry; we’ve got you covered! Zeros of polynomials are, in fact, the solutions to the polynomial equation. In other words, they are the values of the variable (for example, x) that make the polynomial equal to zero. For instance, if we have a simple polynomial like x^2 – 4, the zeros are the values of x that solve the equation x^2 – 4 = 0, which are x = 2 and x = -2. So, in this example, 2 and -2 are the zeros of the polynomial.

But that’s not all. Did you know that the zeros of a polynomial give us critical insights into its graph? That’s right! The zeros correspond to where the graph of the polynomial touches or crosses the x-axis. Fascinating, isn’t it? Let’s take a deeper dive into the world of polynomials and their zeros!

Definition of Polynomials

To truly understand the zeros of polynomials, we must first grasp what a polynomial is. At its core, a polynomial is a mathematical expression comprising variables and coefficients, combined using operations such as addition, subtraction, and multiplication.

Polynomials can range from simple to complex, such as the linear polynomial 2x+1 or a higher degree polynomial like 3x^4 – 2x^2 + 5x – 7. Intriguingly, the degree of a polynomial, which is the highest power of the variable, plays a significant role in determining the number of zeros in the polynomial.

Definition of Zeros in Polynomials

Now that we have a basic understanding of polynomials, let’s dig into the definition of zeros in polynomials. Zeros, also known as roots or solutions of a polynomial, are the values of the variable that make the polynomial equal to zero. For instance, in the polynomial equation x^2 – 3x + 2 = 0, the zeros are x = 1 and x = 2, as these values of x make the polynomial equation hold true.

Properties of Polynomials and Their Zeros

Properties of Polynomials

Polynomials have various fascinating properties that make them a central topic in algebra. One primary characteristic is the Degree of a Polynomial, which is the highest power in the polynomial. The degree determines the maximum number of zeros a polynomial can have. Moreover, the Leading Coefficient (the coefficient of the term with the highest degree) plays a significant role in determining the end behavior of the polynomial’s graph.

Properties of Zeros in Polynomials

The zeros of polynomials also possess intriguing properties. One key aspect is the Fundamental Theorem of Algebra. This theorem states that a polynomial of degree n will have exactly n zeros, considering multiplicity and complex zeros. Furthermore, the Conjugate Zeros Theorem posits that if a polynomial has real coefficients, and a + bi (where ‘a’ and ‘b’ are real numbers, and ‘i’ is the imaginary unit) is a zero, then its conjugate, a – bi, is also a zero.

Difference Between Polynomials and Their Zeros

While polynomials are mathematical expressions involving variables and coefficients, their zeros are the solutions to the equation formed when the polynomial is set to equal zero. The zeros indicate where the polynomial’s graph intersects the x-axis, revealing crucial information about the polynomial’s behavior.

Formulas for Finding Zeros in Polynomials

Different formulas can help in finding the zeros of a polynomial, depending on the polynomial’s degree. For instance, for a quadratic polynomial (degree 2), we use the Quadratic Formula; for a cubic polynomial (degree 3), we can use Cardano’s Formula.

Writing Polynomial Equations Given Zeros

Writing a polynomial equation when the zeros are known involves using the Factor Theorem. For example, if a polynomial has zeros at x = 1, x = -2, and x = 3, the polynomial can be written as f(x) = a*(x – 1)(x + 2)(x – 3), where ‘a’ is a non-zero constant.

Finding Zeros of Polynomials Using Formulas

To find zeros of polynomials, we set the polynomial equal to zero and solve for the variable. Depending on the polynomial’s degree, we can use different methods, including factoring, using the Rational Root Theorem, or applying synthetic division and the Quadratic Formula.

Practice Problems on Zeros of Polynomials

Indeed, practice problems are an excellent way to reinforce your understanding and hone your problem-solving skills. Let’s tackle some problems together!

  1. Find the zeros of the polynomial: f(x) = x^2 – 3x – 4

    Solution: We factor the quadratic expression to get (x – 4)(x + 1) = 0. So, the solutions are x = 4 and x = -1.

  2. Find the zeros of the polynomial: f(x) = 2x^3 – 5x^2 – 4x + 3

    Solution: This one’s a bit trickier. Here, we might need to use the Rational Root Theorem or synthetic division to find the zeros. For simplicity, we’ll say the solutions are x = 1/2, x = -1, and x = 3.

  3. Write a polynomial of degree 3 with zeros at x = 2, x = -1, and x = 0.

    Solution: Using the Factor Theorem, we can write the polynomial as f(x) = a*(x – 2)*(x + 1)*x, where ‘a’ is a non-zero constant.

  4. Given a polynomial f(x) = x^3 – 6x^2 + 11x – 6, verify if x = 1, 2, and 3 are zeros of the polynomial.

    Solution: We substitute these values into the polynomial. If we get zero for all, then these are indeed zeros of the polynomial.

  5. Interpret graphically: Draw the graph of the polynomial f(x) = (x – 1)(x – 2)(x – 3) and mark the zeros.

    Solution: The zeros of the polynomial are at x = 1, x = 2, and x = 3. The graph of this polynomial will cross the x-axis at these points.

Remember, these problems are just a starting point. There are many more complex problems out there, and the more you practice, the better you’ll get at finding and understanding the zeros of polynomials! Happy studying!


In conclusion, we hope this journey through the realm of Zeros of Polynomials has provided you with valuable insights and sparked your curiosity. At Brighterly, we believe in making math engaging, relatable, and, most importantly, fun! The zeros of polynomials, with their ability to tell a story about the polynomial’s behavior, embody that belief. So, whether you’re sketching a graph or solving a complex equation, remember the importance of these zeros, and never underestimate the power of a good zero! Happy exploring, and remember, every journey starts with a single step, or in this case, a single zero!

Frequently Asked Questions on Zeros of Polynomials

What is the importance of finding zeros in polynomials?

Finding the zeros in polynomials is crucial as it helps us solve polynomial equations. It’s also fundamental in sketching the graph of polynomials as zeros indicate where the graph of the polynomial crosses or touches the x-axis. Moreover, they give insights into factors of the polynomial.

How do we find zeros for higher degree polynomials?

Finding zeros for higher degree polynomials often involves more complex methods such as the Rational Root Theorem, synthetic division, and sometimes even numerical methods when a closed-form solution isn’t available. Additionally, some specific formulas apply to polynomials of degree 3 (Cubic) and 4 (Quartic).

Are there always as many zeros as the degree of the polynomial?

Yes, according to the Fundamental Theorem of Algebra, a polynomial of degree n will always have exactly n zeros, if we consider multiplicity and include both real and complex zeros.

Information Sources
  1. Wolfram MathWorld – Polynomial
  2. UCLA Department of Mathematics – Polynomial
  3. Harvard – Polynomials and Polynomial Functions

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