Polynomial equations in A Level Maths introduce students to more complex algebraic structures. These include quadratic, cubic and even quartic equations, each with unique properties and solutions. Understanding the roots of these polynomials is an important step in understanding mathematics that underpins much of the science and engineering worlds.

This article will explore various theorems and formulas that explain polynomial roots, including the Quadratic Formula and Vieta's Formulas. Quiz questions will be included to test your knowledge and we will also discuss the practical applications of polynomial roots. If you need more support learning this topic or in your revision, follow the link for a list of qualified A Level Maths tutors.

## Polynomial Roots in Maths

In its simplest form, a polynomial is an expression containing of variables (also known as indeterminates), coefficients and the operations of addition, subtraction, multiplication and non-negative integer exponents of variables. The roots of a polynomial (often referred to as zeroes) are the values for which the polynomial equation equals zero. These roots are fundamental to solving polynomial equations and understanding their behaviour.

### Types of Polynomials

Polynomials are categorised based on their degree, the highest exponent of the variable in the equation, which is indicative of the polynomial's highest order. The most familiar to many are quadratic polynomials, or simply roots of quadratics, characterised by a degree of two. Quadratic equations, notable for their simplicity and utility in various fields, can be solved in several ways, including factoring, completing the square, and using the quadratic formula. Each method sheds light on how the roots relate to the polynomial's graphical representation, particularly the product of the roots, which is a key concept in understanding these equations.

**Cubic polynomials**- with a degree of three - introduce a layer of complexity, offering situations where there may be one real root and two complex roots, or all three roots are real. These cubic equations are more challenging to solve, requiring techniques such as synthetic division, the Rational Root Theorem, and Cardano's formula. Each techniquefor cubics offers a pathway to resolving the roots of these more complex polynomials, deepening our understanding of the polynomial functions' behaviour.

**Quartic polynomials**- a degree of four - are the highest degree polynomials typically covered in A Level Further Maths. Solving quartic equations can involve methods such as Ferrari's solution. These methods are complex and show the complexity within polynomial equations.

### Significance of Polynomial Roots

Understanding the roots of a polynomial allows mathematicians to solve equations and understand the polynomial function's behaviour. The roots indicate where the graph of the polynomial intersects the x-axis, giving us an insight into the function's properties.

Polynomial roots also play a role in various applications in mathematics and beyond, including physics, engineering and economics. They are used to model and solve real-world problems, from calculating trajectories and forces to optimising financial models.

The University of Cambridge offers an introduction to polynomials that includes additional resources and practice problems. This can complement your study by providing a broader context and deeper understanding of polynomials and their applications.

## Concepts and theorems for A Level Maths

If we look in more detail at the study of polynomial roots, there is a wealth of theorems and concepts designed to explain these mathematical expressions. For students following the Edexcel curriculum, these principles are particularly pertinent, forming an essential part of their mathematical foundation.

We will explore these principles below to help our understanding of polynomial equations.

### Factor theorem

The Factor Theorem states that if a polynomial

*f(x)*has a root at*x=a*, then x-a is a factor of*f(x)*. This theorem not only helps identify the roots of a polynomial but also factors it into simpler components, each representing a step closer to uncovering all roots, including whose roots can be explicitly determined.Consider the polynomial

*f(x) = x*. Let's say we want to check if^{3}-7x+6*x=1*is a root of this polynomial.Substituting

*x=1*into*f(x)*, we get:*f(1) = 1*

^{3}-7(1)+6=0Since

*f(1) = 0*, by the Factor Theorem,*x-1*is a factor of*f(x)*.### Remainder theorem

The Remainder Theorem is closely related and is a quick way to calculate the remainder of a polynomial

*f(x)*when divided by a linear factor*(x-a)*. This theorem is particularly useful for verifying potential roots without fully dividing the polynomial, serving as a preliminary check for possible factors and, by extension, roots.Using the same polynomial

*f(x) = x*, let's calculate the remainder when^{3}-7x+6*f(x)*is divided by*x-2*.Substituting

*x=2*into*f(x)*, we find:*f(2) = 2*

^{3}-7(2)+6 = 8-14+6=0The remainder is

*0*, indicating that*x-2*is a factor of*f(x)*, and*x=2*is a root of the polynomial.### Vieta's formulas

Vieta's Formulas provide a direct relationship between the roots of a polynomial and its coefficients, specifically the product of the roots. These formulas are invaluable in situations where calculating the roots explicitly might be cumbersome. They allow students, especially those preparing for Edexcel exams, to grasp the sum and product of roots based on the polynomial's coefficients, offering insights into the nature of these roots without solving the equation fully.

For a quadratic polynomial

*f(x) = ax*, with roots^{2}+bx+c*r*and_{1}*r*, Vieta's Formulas state:_{2}- The sum of the roots:
*r*_{1}+r_{2}=-b/a - The product of the roots:
*r*_{1 . }r_{2}=c/a

Consider the quadratic equation

*x2-5x+6 = 0*. Without solving for the roots directly, we can use Vieta's Formulas to find:- The sum of the roots:
*r*_{1}+r_{2}=5/1=5 - The product of the roots:
*r*_{1 . }r_{2}=6/1=6

These relationships tell us that the two roots of this equation, when added together, will equal 5, and when multiplied, will equal 6. Solving this particular equation directly, we find the roots are 3 and 2, which satisfy both conditions set by Vieta's Formulas.

## Application in problem solving

These theorems are used to solve real-world problems where polynomial equations model natural phenomena, economic trends, or engineering challenges. Understanding the roots helps predict outcomes, optimise processes and develop new theories across disciplines.

To further enrich your study and application of these concepts, resources such as Wolfram Alpha's computational engine provide a platform to explore and visualise polynomial equations and their roots.

### 1

Which theorem provides a quick way to check if a given value is a root of a polynomial?

## "Core Pure" mathematics

"Core Pure" mathematics is an important component of A Level Further Maths. It focuses on advancing the understanding of key topics by combining theoretical and applied mathematics. This provides the foundational knowledge and analytical skills needed to tackle complex mathematical challenges.

When discussing the roots of polynomials, "Core Pure" mathematics bridges theoretical mathematics with practical application. It lets us engage deeply with advanced mathematical theories and problems.

### The significance of Polynomial Roots in "Core Pure"

"Core Pure" mathematics is designed to challenge students, encouraging them to engage with complex mathematical theories and problems. The roots of polynomials play a pivotal role in this endeavour. As students explore quadratic, cubic and quartic equations within "Core Pure", they explore the complexities of algebra and calculus, learning the implications of these roots in various contexts.

Understanding polynomial roots within "Core Pure" is about developing a deep appreciation for the structure and behaviour of mathematical functions. This knowledge gives students the tools needed to tackle advanced topics in mathematics and beyond.

### Integrating Polynomial Roots into "Core Pure" studies

"Core Pure" mathematics encourages an integrated approach to learning, where students are expected to connect different areas of mathematics. The study of polynomial roots is a good example, combining topics such as differentiation, integration and numerical methods. Students can better visualise the functions by understanding the roots, solving differential equations and applying these concepts in real-world scenarios.

### 2

Which area of "Core Pure" mathematics is affected by the understanding of polynomial roots?

## Practical applications

The theoretical knowledge of polynomial roots plays a crucial role in practical applications. Learning about the roots of polynomials helps us bridge the gap between abstract mathematical concepts and real-world problems, applying their skills to - among others - physics, engineering, economics and computer science.

**Physics and engineering**

In physics and engineering, polynomial equations are used to model and solve problems related to motion, forces and energy. For example, the trajectory of a projectile can be represented by a quadratic equation, where the roots show the points where the projectile will hit the ground. Similarly, in electrical engineering, polynomials help design circuits and understand resonance frequencies.

**Economics**

In economics, polynomials can model supply and demand curves, profit maximisation and cost functions. The roots of these polynomial equations show equilibrium points or optimal pricing strategies, providing valuable insights for decision-making and policy formulation.

**Computer science**

Computer science utilises polynomial algorithms for data encryption, coding theory and the development of efficient algorithms for problem-solving. The complexity of these algorithms depends on the nature of the polynomial roots, influencing their performance and applicability in different scenarios.

### 3

Which field uses polynomial equations to model the trajectory of a projectile?

## Conclusion

The roots of polynomials are important to understanding the language of mathematics. From the fundamental theorems that guide our solving techniques to the practical applications that bridge theory and real-world problems, polynomial roots are integral to mathematical reasoning.

Make sure to use resources and revision notes to strengthen your understanding of this topic. Learning about the roots of polynomials, from whose roots we seek to understand to the product of the roots, provides an insight into the fundamental aspects of A Level Maths. If you need further support, you may consider viewing the link for a selection of specialised A Level Maths tutors.

## Glossary

- Algebra - This deals with symbols and the rules for manipulating these symbols; it is a unifying topic of almost all mathematics.
- Coefficient - A number or constant quantity placed before and multiplying the variable in an algebraic expression.
- Cubic Polynomial - A polynomial of degree three, meaning its highest exponent is three. It takes the general form
*ax^3 + bx^2 + cx + d*, where*a ? 0*. - Degree - The highest power (exponent) of the variable in a polynomial equation. It indicates the most significant term of the polynomial.
- Differentiation - The process of finding the derivative of a function, which measures how a function changes as its input changes.
- Factor Theorem - A theorem stating that a polynomial
*f(x)*has a factor*(x - a)*if and only if*f(a) = 0*, meaning*a*is a root of the polynomial. - Integration - The process of finding the integral of a function, which is the reverse process of differentiation and can be interpreted as finding the area under the curve of a graph.
- Polynomial - An expression consisting of variables (indeterminates) and coefficients, involving only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables.
- Quadratic Polynomial - A polynomial of degree two, meaning its highest exponent is two.
- Quartic Polynomial - A polynomial of degree four, meaning its highest exponent is four.
- Remainder Theorem - A theorem that provides a method for evaluating the remainder of the division of a polynomial by a linear divisor of the form
*(x - a).* - Roots - The values of x that satisfy the polynomial equation
*f(x) = 0*. Roots are also referred to as zeros or solutions of the equation. - Vieta's Formula - Formulas that relate the coefficients of a polynomial to sums and products of its roots. They provide a way to understand the relationship between the roots and the polynomial's coefficients without solving the equation.