Adding or subtracting the same value to both sides of an equation without maintaining the equality

Oct 13, 2025 by wbrum.org 79 views

Introduction

In mathematics, solving linear equations is a fundamental concept that students encounter in various stages of their academic journey. However, the process of solving these equations can sometimes lead to confusion, especially when different students arrive at different solutions. In this article, we will examine a case study of two students, David and Michael, who are presented with the equation $x - 15 = 5$ . We will analyze their approaches and determine which solution is correct.

The Equation

The given equation is $x - 15 = 5$ . This is a linear equation in one variable, where the variable is $x$ . The equation is in the form of $ax = b$ , where $a$ is the coefficient of the variable, and $b$ is the constant term.

David's Approach

David says that $x = 20$ . To understand how David arrived at this solution, let's examine his thought process. David likely added 15 to both sides of the equation, resulting in $x = 20$ . This approach is based on the concept of inverse operations, where adding the same value to both sides of an equation maintains the equality.

Michael's Approach

Michael, on the other hand, says that $x = -10$ . To understand Michael's thought process, let's examine his approach. Michael likely added 15 to both sides of the equation, but then subtracted 25 from both sides, resulting in $x = -10$ . This approach is also based on the concept of inverse operations, but Michael's solution is incorrect.

Analysis

To determine which solution is correct, let's analyze the equation $x - 15 = 5$ . The first step in solving this equation is to isolate the variable $x$ . To do this, we need to add 15 to both sides of the equation. This results in $x = 20$ . Therefore, David's solution is correct.

Why Michael's Solution is Incorrect

Michael's solution is incorrect because he added 15 to both sides of the equation, but then subtracted 25 from both sides. This is not a valid operation, as it changes the value of the equation. In mathematics, when we add or subtract the same value to both sides of an equation, we must maintain the equality. In this case, Michael's solution is incorrect because he introduced an extraneous step that altered the value of the equation.

Conclusion

In conclusion, David's solution is correct, and Michael's solution is incorrect. The correct solution to the equation $x - 15 = 5$ is $x = 20$ . This solution is based on the concept of inverse operations, where adding the same value to both sides of an equation maintains the equality. We hope that this case study has provided insight into the importance of following the correct steps when solving linear equations.

Common Mistakes to Avoid

When solving linear equations, there are several common mistakes to avoid. These include:

Adding or subtracting the same value to both sides of an equation without maintaining the equality
Introducing extraneous steps that alter the value of the equation
Failing to isolate the variable

By avoiding these common mistakes, students can ensure that their solutions are correct and accurate.

Real-World Applications

Linear equations have numerous real-world applications. Some examples include:

Finance: Linear equations are used to calculate interest rates, investment returns, and other financial metrics.
Science: Linear equations are used to model population growth, chemical reactions, and other scientific phenomena.
Engineering: Linear equations are used to design and optimize systems, such as bridges, buildings, and electronic circuits.

By understanding how to solve linear equations, students can develop problem-solving skills that are essential in a wide range of fields.

Final Thoughts

Introduction

In our previous article, we examined a case study of two students, David and Michael, who were presented with the equation $x - 15 = 5$ . We analyzed their approaches and determined that David's solution was correct, while Michael's solution was incorrect. In this article, we will provide a Q&A guide to help students understand how to solve linear equations.

Q: What is a linear equation?

A: A linear equation is an equation in which the highest power of the variable is 1. In other words, a linear equation is an equation that can be written in the form of $ax = b$ , where $a$ is the coefficient of the variable, and $b$ is the constant term.

Q: How do I solve a linear equation?

A: To solve a linear equation, you need to isolate the variable. This can be done by adding or subtracting the same value to both sides of the equation, or by multiplying or dividing both sides of the equation by the same non-zero value.

Q: What is the first step in solving a linear equation?

A: The first step in solving a linear equation is to add or subtract the same value to both sides of the equation in order to isolate the variable. This is based on the concept of inverse operations, where adding the same value to both sides of an equation maintains the equality.

Q: How do I know if my solution is correct?

A: To determine if your solution is correct, you need to check if it satisfies the original equation. This can be done by plugging your solution back into the original equation and checking if the equation holds true.

Q: What are some common mistakes to avoid when solving linear equations?

A: Some common mistakes to avoid when solving linear equations include:

Adding or subtracting the same value to both sides of an equation without maintaining the equality
Introducing extraneous steps that alter the value of the equation
Failing to isolate the variable

Q: How do I apply linear equations in real-world situations?

A: Linear equations have numerous real-world applications. Some examples include:

Finance: Linear equations are used to calculate interest rates, investment returns, and other financial metrics.
Science: Linear equations are used to model population growth, chemical reactions, and other scientific phenomena.
Engineering: Linear equations are used to design and optimize systems, such as bridges, buildings, and electronic circuits.

Q: What are some tips for solving linear equations?

A: Some tips for solving linear equations include:

Read the equation carefully and understand what is being asked
Use inverse operations to isolate the variable
Check your solution by plugging it back into the original equation
Avoid common mistakes, such as adding or subtracting the same value to both sides of an equation without maintaining the equality

Conclusion

In conclusion, solving linear equations is a fundamental concept in mathematics that requires attention to detail and a clear understanding of the underlying principles. By following the correct steps and avoiding common mistakes, students can ensure that their solutions are accurate and reliable. We hope that this Q&A guide has provided insight into the importance of solving linear equations and has inspired students to develop their problem-solving skills.

Additional Resources

For additional resources on solving linear equations, including practice problems and interactive tools, please visit the following websites:

Khan Academy: Khan Academy offers a comprehensive guide to solving linear equations, including video tutorials and practice problems.
Mathway: Mathway is an online math problem solver that can help students solve linear equations and other math problems.
Purplemath: Purplemath is a website that offers a wide range of math resources, including tutorials, examples, and practice problems on solving linear equations.