## I. Introduction

If you are studying mathematics, you have surely encountered a system of equations. Solving systems of equations is an essential skill for a variety of fields including engineering, economics, and finance. In this article, we will explore how to solve systems of equations step-by-step, provide real-life examples, and offer tips on how to avoid common mistakes.

## II. Understanding Systems of Equations

If you are not familiar with systems of equations, let’s start with a definition. A system of equations consists of two or more equations that contain the same variables. In most cases, we solve for two variables using two equations. There are three types of systems of equations: linear, non-linear, and inconsistent.

Linear equations are two or more lines with one or more common variables. They can be parallel, intersecting, or coincident. Non-linear equations are not straight lines, and they can have different shapes. Inconsistent equations are two or more equations that cannot be satisfied at the same time.

To solve a system of equations, you need to find the values of the variables that satisfy both equations. Some systems have one solution, while others have multiple solutions or no solution.

## III. Step-by-Step Guide to Solving a System of Equations

Now let’s explore three different methods to solve a system of equations: the substitution method, the elimination method, and the graphing method.

### A. The Substitution Method

The substitution method involves solving one equation for one variable and then substituting the expression into the other equation. Here’s how it works:

- Choose one equation and solve for one variable.
- Substitute the expression into the other equation.
- Solve for the second variable.
- Substitute the value of the second variable into the equation in step 1 and solve for the first variable.
- Check the solution by substituting both variables into both equations.

Let’s use an example to illustrate the method.

Example:

*x + 2y = 7*

*3x – 4y = -5*

- Solve the first equation for x:
*x = 7 – 2y*. - Substitute the expression into the second equation:
*3(7 – 2y) – 4y = -5*. - Solve for y:
*y = 1*. - Substitute the value of y into the equation in step 1:
*x = 5*. - Check the solution by substituting both variables into both equations to verify that both equations hold true.

### B. The Elimination Method

The elimination method involves adding or subtracting the equations to eliminate one variable. Here’s how it works:

- Multiply one or both equations by a constant to make the coefficients of one variable add up or subtract to zero.
- Add or subtract the equations to eliminate that variable.
- Solve for the remaining variable.
- Substitute the value of the variable into one of the original equations to find the other variable.
- Check the solution by substituting both variables into both equations.

Let’s use an example to illustrate the method.

Example:

*2x + 3y = 14*

*4x – y = 17*

- Multiply the second equation by two to make the coefficient of y equal to -6:
*8x – 2y = 34*. - Add the equations:
*10x = 48*. - Solve for x:
*x = 4.8*. - Substitute the value of x into one of the original equations to solve for y:
*y = -7.4*. - Check the solution by substituting both variables into both equations to verify that both equations hold true.

### C. The Graphing Method

The graphing method involves graphing both equations on the same coordinate plane and finding the intersection point. Here’s how it works:

- Graph both equations on the same coordinate plane.
- Find the intersection point of the two lines.
- Read the coordinates of the intersection point.
- Check the solution by substituting both variables into both equations.

Let’s use an example to illustrate the method.

Example:

*2x + y = 6*

*x – y = -2*

- Graph both equations on the same coordinate plane.
- Find the intersection point of the two lines:
*(2, 0)*. - The solution is
*x = 2*and*y = 0*. - Check the solution by substituting both variables into both equations to verify that both equations hold true.

## IV. Practice Worksheets of Systems of Equations

To get more comfortable with solving systems of equations, it’s recommended to practice with worksheets. Here are some examples of different types of equations and their detailed solutions.

### A. Different types of equations with detailed solutions

*2x – y = 4*; *3x + y = 7*

Solution: *x = 2, y = 0.5*

*4x + 3y = 9*; *5x – 2y = 8*

Solution: *x = 2.08, y = 0.67*

### B. Step-by-step explanations of each solution

To help you better understand each method of solving systems of equations, we have provided step-by-step explanations of each solution, along with an example problem.

## V. Relating Systems of Equations to Real-Life Scenarios

Systems of equations are widely used in real-world situations. For example, they can help you calculate the cost of buying different items or find the optimal solution to a problem.

### A. Example problems and how to solve them

**Calculating the cost of buying different items:**

You want to buy four bottles of water and five packs of gum, but you only have $10. You know that a bottle of water costs $1.50 and a pack of gum costs $0.75. How much change will you receive?

- Define the variables:
*x = number of bottles of water*,*y = number of packs of gum*. - Write the equations:
*1.5x + 0.75y = 10*and*x + y = 9* - Solve the system by any method.
- The solution is:
*x = 3*and*y = 6*. - The cost of buying four bottles of water and five packs of gum is $9.75, and the change is $0.25.

**Optimal solutions to real-life situations:**

You work in a store that sells two products: product A and product B. You know that you can sell 20 units of product A per day and 35 units of product B per day. However, you cannot sell more than 60 units of both products combined per day. Product A costs $2 per unit and product B costs $3 per unit. What is the maximum revenue you can generate per day?

- Define the variables:
*x = units of product A*,*y = units of product B*. - Write the equations:
*2x + 3y = revenue*and*x + y ≤ 60*,*x ≤ 20*,*y ≤ 35* - Solve the system by graphing.
- The maximum revenue per day is $130.

## VI. Common Pitfalls in Solving Systems of Equations

While solving systems of equations is relatively straightforward, there are several common mistakes people make. Here are some tips and tricks to avoid or correct these mistakes:

- Always check your answers at the end by substituting the variables into both equations.
- Be careful with negative signs and fractions.
- Do not cross multiply when multiplying equations.
- When adding or subtracting equations, make sure you eliminate one variable at a time.

## VII. Conclusion

Solving systems of equations is an essential skill for many different fields. By understanding the different types of systems of equations, three methods for solving them, and some real-life examples, you can be confident in your ability to solve them. Remember to practice and check your answers to avoid common mistakes.

Now that you have completed this guide, you can confidently apply this knowledge to real-life problems and continue to improve your maths skills.