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Solved x2-11x+28=0 Quadratic Equation

by Ram Internet

Quadratic equations are foundational elements in the world of algebra, offering insights into various mathematical and real-world phenomena. Among these, the equation ( x2-11x+28=0 ) stands as a quintessential example, showcasing the elegance and intricacy of quadratic solutions. This article aims to demystify this specific quadratic equation, providing a clear understanding of its nature, solutions, and applications.

At first glance, ( x2-11x+28=0 ) may appear as just another mathematical puzzle. However, it holds much more significance. This equation is not only a gateway to mastering quadratic equations but also serves as a bridge to understanding more complex mathematical concepts. By exploring its solutions, we can gain insights into the behavior of parabolic functions, which find applications in diverse fields such as physics, engineering, and economics.

Our journey through this equation will take us from the basics of quadratic equations to more advanced concepts. We will explore different methods of solving this equation, including factorization, the quadratic formula, and completing the square. Each method offers a unique perspective and enhances our problem-solving skills.

Additionally, we will delve into the graphical representation of ( x2-11x+28=0 ), illustrating how the abstract translates into the visual. This graphical perspective not only aids in understanding the equation’s roots but also provides a deeper appreciation of the properties of quadratic functions, such as symmetry and vertex location.

By the end of this article, you will not only be able to solve (x2-11x+28=0 ) with ease but also appreciate its broader implications in mathematics and beyond. Whether you’re a student, educator, or simply a curious mind, this exploration promises to enrich your understanding of one of algebra’s most intriguing subjects. Let’s embark on this mathematical adventure together, unraveling the mysteries hidden within ( x2-11x+28=0 ).


Background on Quadratic Equations

As a professor delving into the fascinating world of quadratic equations, it is essential to establish a strong foundational understanding of these equations. A quadratic equation is a second-degree polynomial equation of the form ( ax^2 + bx + c = 0 ), where ( a ), ( b ), and ( c ) are constants, and ( a \neq 0 ). The solution of these equations is fundamental in various mathematical and scientific fields.

Historical Perspective

The study of quadratic equations dates back to ancient civilizations, including the Babylonians, Greeks, and Indians. The methods and solutions developed over centuries have significantly contributed to the advancement of algebra. Quadratic equations were among the first to be solved algebraically, marking a significant milestone in the history of mathematics.

General Characteristics

  • Degree: Quadratic equations are characterized by their highest power, which is two. This is what differentiates them from linear (first-degree) and cubic (third-degree) equations.
  • Standard Form: The most recognized form of a quadratic equation is ( ax^2 + bx + c = 0 ). However, it can also be represented in other forms like vertex form or factored form, depending on the application.
  • Coefficients: The coefficients ( a ), ( b ), and ( c ) play crucial roles in determining the nature of the equation’s graph and roots. The coefficient ( a ) influences the parabola’s opening direction and width.

The Parabola

  • Graphical Representation: When plotted on a graph, quadratic equations form a parabola, a U-shaped curve. The direction (upwards or downwards) of the parabola is determined by the sign of ( a ).
  • Vertex and Axis of Symmetry: The vertex is the highest or lowest point on the parabola, and the axis of symmetry is a vertical line that passes through the vertex, dividing the parabola into two symmetrical halves.
  • Intercepts: Quadratic equations may have zero, one, or two x-intercepts (roots), and one y-intercept.

Roots of Quadratic Equations

The roots of a quadratic equation are the values of ( x ) that satisfy the equation. They represent the points where the parabola intersects the x-axis. There are several methods to find these roots, including:

  • Factorization: Expressing the quadratic equation as a product of two binomials.
  • Quadratic Formula: A universal method that uses the coefficients ( a ), ( b ), and ( c ) to find the roots.
  • Completing the Square: Transforming the equation into a perfect square trinomial.


The discriminant of a quadratic equation, denoted as ( \Delta ) and calculated as ( b^2 – 4ac ), provides crucial information about the nature of the roots:

  • Positive Discriminant: Indicates two distinct real roots.
  • Zero Discriminant: Indicates one real root (a repeated root).
  • Negative Discriminant: Indicates complex roots.


Quadratic equations are not just theoretical constructs; they have practical applications in various fields:

  • Physics: Describing projectile motion, free fall, and other phenomena.
  • Engineering: Designing structures, analyzing forces, and optimization problems.
  • Economics: Modeling cost functions, revenue functions, and market equilibrium analysis.

In conclusion, understanding quadratic equations is not just about solving for ( x ); it’s about comprehending a fundamental concept that bridges various disciplines. The equation ( x2-11x+28=0 ) is a classic example that encapsulates all these aspects, serving as a perfect specimen for our exploration.

Solving the Equation x2-11x+28=0

As a professor exploring the intricacies of quadratic equations, let’s dive into the detailed methods of solving the specific equation ( x2-11x+28=0 ). This equation, while seemingly simple, provides a rich context for understanding the various techniques used in solving quadratic equations.

1. Factorization Method

The first approach is to factorize the quadratic equation. Factorization involves expressing the quadratic equation as a product of two binomials.

  • Step 1: Look for two numbers that multiply to ( c ) (which is 28 in our case) and add up to ( b ) (which is -11). In this equation, those numbers are -4 and -7, since ((-4) \times (-7) = 28) and ((-4) + (-7) = -11).
  • Step 2: Rewrite the equation as ( (x – 4)(x – 7) = 0 ).
  • Step 3: Set each factor equal to zero: ( x – 4 = 0 ) and ( x – 7 = 0 ).
  • Step 4: Solve for ( x ) in each case, yielding the roots ( x = 4 ) and ( x = 7 ).

2. Quadratic Formula

The quadratic formula is a universal method that can be used to find the roots of any quadratic equation. The formula is ( x = \frac{-b \pm \sqrt{b^2 – 4ac}}{2a} ).

  • Step 1: Identify ( a ), ( b ), and ( c ) from the equation. Here, ( a = 1 ), ( b = -11 ), and ( c = 28 ).
  • Step 2: Plug these values into the quadratic formula: ( x = \frac{-(-11) \pm \sqrt{(-11)^2 – 4 \cdot 1 \cdot 28}}{2 \cdot 1} ).
  • Step 3: Simplify under the square root: ( x = \frac{11 \pm \sqrt{121 – 112}}{2} ).
  • Step 4: Further simplify: ( x = \frac{11 \pm \sqrt{9}}{2} ).
  • Step 5: Solve for ( x ), giving two solutions: ( x = \frac{11 \pm 3}{2} ), which are ( x = 4 ) and ( x = 7 ).

3. Completing the Square

Completing the square is a method that involves transforming the quadratic equation into a perfect square trinomial.

  • Step 1: Rewrite the equation in the form ( x^2 + bx = -c ). For our equation, it becomes ( x^2 – 11x = -28 ).
  • Step 2: Add (\left(\frac{b}{2}\right)^2) to both sides. Here, ( b = -11 ), so (\left(\frac{-11}{2}\right)^2 = 30.25). The equation becomes ( x^2 – 11x + 30.25 = 2.25 ).
  • Step 3: Rewrite the left side as a squared binomial: ( (x – 5.5)^2 = 2.25 ).
  • Step 4: Take the square root of both sides: ( x – 5.5 = \pm \sqrt{2.25} ).
  • Step 5: Solve for ( x ), resulting in ( x = 5.5 \pm 1.5 ), which gives ( x = 4 ) and ( x = 7 ).

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Applications of the Quadratic Equation ( x2-11x+28=0 )

As a professor examining the quadratic equation (x2-11x+28=0 ), it is crucial to explore its applications beyond the classroom. This equation, while a simple mathematical expression, can be a model for various real-world phenomena. Understanding these applications not only enriches the learning experience but also showcases the practical utility of quadratic equations.

1. Physics and Engineering

In physics, quadratic equations frequently arise in the context of projectile motion and kinematics. For example, the equation ( x2-11x+28=0 ) can represent a scenario in projectile motion where ( x ) could signify the time elapsed, and the equation gives specific times when the projectile reaches certain heights or distances.

In engineering, such equations are essential in designing parabolic paths or structures. The parameters of the equation can represent dimensions or forces acting on a structure, offering insights into optimal design and stability.

2. Economics and Business

In the field of economics, quadratic equations can be used to model cost, revenue, or profit functions. The roots of the equation ( x2-11x+28=0 ) might represent break-even points in a business model, where revenue equals cost, indicating no profit or loss.

Similarly, in investment analysis, such equations can help in determining the maximum profit or loss, or the conditions under which a certain return on investment is achieved.

3. Biology and Environmental Science

Quadratic equations have their place in biology for modeling population dynamics or the spread of diseases. The equation ( x2-11x+28=0) could, for instance, represent a model where the population size or the number of infected individuals is a function of time or another variable.

In environmental science, such equations can be used to model growth patterns of plants or the spread of pollutants under certain conditions.

4. Optimization Problems

Quadratic equations are integral in solving optimization problems across various fields. For example, in logistics and operations, the equation ( x^2 – 11x + 28 = 0 ) can be part of a larger model to minimize costs or maximize efficiency in a supply chain.

5. Art and Architecture

In art and architecture, the parabolic shapes described by quadratic equations, such as (x2-11x+28=0), influence design and aesthetic choices. The symmetry and curvature inherent in these equations can guide the creation of visually pleasing and structurally sound designs.


In exploring the quadratic equation ( x2-11x+28=0 ), we have journeyed through a landscape rich in mathematical concepts and real-world applications. This exploration has not only demystified the process of solving such an equation through various methods like factorization, the quadratic formula, and completing the square but has also illuminated the profound implications of quadratic equations in diverse fields.

From the parabolic trajectories in physics and engineering to the modeling of economic trends, and from biological dynamics to architectural designs, this equation exemplifies the ubiquity and versatility of quadratic equations. It serves as a compelling testament to the seamless integration of abstract mathematical principles with practical scenarios, offering solutions and insights into complex problems.

As we conclude, it becomes evident that the study of quadratic equations, exemplified by ( x^2 – 11x + 28 = 0 ), is not confined to the realms of academic curiosity. Instead, it is a fundamental tool that bridges theoretical mathematics with the tangible challenges and innovations of the real world. This article, therefore, stands as an invitation to both students and professionals to delve deeper into the fascinating world of quadratic equations, appreciating their elegance and embracing their utility in our daily lives.

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