How To Solve Linear Equations In Two Variables?

How To Solve Linear Equations In Two Variables

Linear equations in two variables serve as fundamental tools in the world of mathematics, offering insights into the relationships between two unknowns. Whether in algebraic expressions or real-world applications, the ability to solve these equations is a crucial skill. In this comprehensive guide, we will delve into the details of how to solve linear equations in two variables, exploring various methods, practical applications, and essential tips to master this essential skill.

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Understanding the Basics: Linear Equations

Before we embark on the journey of solving linear equations in two variables, it’s essential to grasp the basics. These equations take the form:

Ax + By = C, 

  • where A, B, and C are constants, 
  • and x and y are the variables. 

Visualizing these equations on a coordinate plane provides a geometric understanding of their solutions, emphasizing the intersection point as the solution to the system.

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How to Solve Linear Equations in Two Variables?

  1. Substitution Method

The substitution method is a powerful technique for solving systems of linear equations. In this approach, one variable is isolated in one equation and substituted into the other equation.

This method allows for the simplification of equations and the identification of the values of x and y.

For example, consider the system:



By isolating x in the first equation, we get =6 −3/2y, which can be substituted into the second equation. Solving for y and substituting the value back into the original equation yields the solution to the system.

Let’s consider a system of linear equations and apply the Substitution Method to find the solution.


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In the second equation, y is already isolated, so we can substitute this expression for y into the first equation:


Now, distribute the -2:


Combine like terms:




Now that we have the value for x, we can substitute it back into the second equation to find y:



So, the solution to the system of equations is 

x=−5 and y=−11.

  1. Elimination Method

The elimination method involves manipulating the equations to eliminate one variable when added or subtracted. By multiplying one or both equations, the coefficients of one variable can be adjusted to allow for the elimination of that variable when the equations are combined.

Let’s consider the system:



Multiplying the first equation by 3 and the second by 2 allows for the elimination of y when the equations are added. Solving for x and substituting the value back into the original equation yields the solution to the system.

Certainly! Let’s consider the following system of linear equations:



We can use the elimination method to solve this system. Here are the steps:

Step 1: To get the opposites of the coefficients of one variable (either both positive or both negative), multiply one or both equations by a constant. In this instance, the coefficients of y opposites may be obtained by multiplying the first equation by three and the second equation by two:



Step 2: Add the two equations to eliminate the y variable:


Step 3: Solve for X: 

x= 13/32

Step 4: To combine the fractions on the right side, find a common denominator, which is 13:

3(13/32 )+2y=14

First, simplify the expression on the left side:

96/13 + 2y =14

2y= 182/13​ − 96/13

Step 5: Now, solve for y by dividing both sides by 2:

y= 43/13

  1. Graphical Method

Graphing linear equations in two variables provides a visual representation of their intersection point, which is the solution to the system. By plotting the equations on a coordinate plane and identifying the point of intersection, the values of x and y can be determined.

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Special Cases and Considerations For Solving Linear Equation

In the journey of solving linear equations in two variables, it’s crucial to be aware of special cases. Inconsistent and dependent systems, as well as scenarios where no solution exists, require careful consideration.

Inconsistent and Dependent Systems

An inconsistent system has no solution, indicating that the equations represent parallel lines that never intersect. On the other hand, a dependent system has infinitely many solutions, indicating that the equations represent overlapping lines.

Consider the system:



By simplifying the second equation, we see that it is a multiple of the first. This system is dependent, with infinitely many solutions.

No Solution Scenario

In cases where the elimination method results in contradictory statements (e.g., 0 = 5), the system has no solution. This indicates that the equations represent parallel lines with no point of intersection.

Tips and Tricks for Efficient Solving

As with any mathematical skill, efficient solving of linear equations in two variables involves employing strategic tips and tricks.

  1. Identifying Patterns in Equations: Recognizing patterns in equations can expedite the solving process. For example, if two equations have the same coefficients but different constants, the system is inconsistent.
  1. Simplifying Equations Before Solving: Simplifying equations before solving can reduce the complexity of calculations. Factoring common terms or reducing fractions can make the equations more manageable.
  1. Checking Solutions for Accuracy: After obtaining values for x and y, it’s essential to check the solutions by substituting them back into the original equations. This step ensures the accuracy of the solution and helps identify any errors in the solving process.

Applications of Linear Equation in the Real World

The practical applications of solving linear equations in two variables extend beyond the realm of mathematics. In various fields such as economics, physics, and engineering, these equations model relationships and aid in problem-solving.


Linear equations in two variables are commonly used in economics to model supply and demand relationships, production costs, and revenue functions.

By solving these equations, economists can make informed decisions regarding optimal production levels, pricing strategies, and resource allocation.

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In physics, linear equations in two variables play a crucial role in modeling physical phenomena. For instance, equations representing the motion of an object in two-dimensional space involve variables such as time, velocity, and position.

Solving these equations allows physicists to predict the trajectory and behavior of objects in motion.


Engineers utilize linear equations in two variables to analyze and design systems. Whether it’s electrical circuits, structural elements, or fluid dynamics, the relationships between variables are often modeled using linear equations. 

Solving these equations aids engineers in optimizing designs and ensuring the functionality of their systems.

Practice Makes Perfect: Solve Linear Equations In Two Variables

To truly master the art of solving linear equations in two variables, consistent practice is key. A compilation of practice exercises, ranging from basic to complex systems, provides the opportunity to reinforce the learned concepts and enhance problem-solving skills.

  • Online Resources and Tools for Additional Practice

A wide range of online materials and technologies are available in the digital era to augment conventional schooling. Students can interact with the information in a variety of ways via interactive webpages, video lessons, and practice platforms, which accommodate different learning styles.

Common Mistakes and How to Avoid Them

As with any mathematical concept, there are common mistakes that learners may encounter when solving linear equations in two variables. Awareness of these pitfalls and strategies to avoid them is crucial for success.

  1. Misinterpretation of Equations

Misinterpreting the given equations can lead to errors in the solving process. Carefully read and understand the problem statement to ensure accurate representation of the relationships between variables.

  1. Errors in Substitution and Elimination

In the substitution and elimination methods, errors can occur during the manipulation of equations. Double-checking each step and being mindful of signs and coefficients can help avoid these mistakes.

  1. Graphing Pitfalls

When graphing linear equations, accuracy in plotting points and drawing lines is essential. Utilize graph paper and take the time to ensure precision in the graphical representation of equations.


In conclusion, mastering how to solve linear equations in two variables is a valuable skill with applications extending far beyond the realms of mathematics.

By understanding the basics, exploring various solving methods, considering special cases, and incorporating practical applications, learners can enhance their problem-solving abilities. 

With diligent practice, utilization of online resources, and awareness of common mistakes, students can confidently tackle the challenges posed by systems of linear equations, paving the way for success in mathematics and beyond.