Solving Linear Equations in Two Variables

Study Notes

Equation in Two Variables

An equation in two variables refers to a mathematical statement that connects two variables with the use of the equality operator (=). The variables can take any value within a specified domain, and the equation can be expressed as a straight line when plotted on a graph. In this article, we will focus on linear equations, which are equations of the first degree in two variables.

Linear Equations

A linear equation in two variables is an equation that can be written in the slope-intercept form, y = mx + b, where m is the slope and b is the y-intercept. The slope represents the rate of change of the variable y with respect to the variable x, while the y-intercept represents the value of y when x = 0.

The general form of a linear equation in two variables is:

$$Ax + By = C$$

Here, A, B, and C are constants, and x and y are the variables. To find the slope and y-intercept of this equation, we can rewrite it in the slope-intercept form by solving for y:

$$y = \frac{-A}{B}x + \frac{C}{B}$$

The slope of this equation is $$\frac{-A}{B}$$, and the y-intercept is $$\frac{C}{B}$$.

Solving Linear Equations

To solve a linear equation in two variables, we can use the following steps:

Graph the equation: Plot the equation on a graph and determine the domain and range of the variables.
Identify the variables: Determine which variable is dependent and which is independent. This can often be done by looking at the domain and range of the variables.
Solve for one variable: Solve for one of the variables in terms of the other variable. This can be done using the principle of substitution or elimination.
Substitute the value: Substitute the value of the variable you solved for into the equation to find the value of the other variable.

For example, consider the following linear equation:

$$2x + 3y = 6$$

To solve for x and y, we can follow these steps:

Graph the equation: Plot the equation on a graph and determine the domain and range of the variables.
Identify the variables: In this case, both x and y are dependent variables.
Solve for one variable: We can solve for y in terms of x by rearranging the equation:

$$y = \frac{-2}{3}x + \frac{6}{3}$$

$$y = \frac{-2}{3}x + 2$$

Now, we have solved for y in terms of x.

Substitute the value: To find the value of y when x = 3, substitute x = 3 into the equation:

$$y = \frac{-2}{3}(3) + 2$$

$$y = \frac{-6}{3} + 2$$

$$y = -2 + 2$$

$$y = 0$$

So, when x = 3, y = 0.

Applications of Linear Equations

Linear equations have numerous applications in various fields, such as physics, engineering, and economics. For example, they can be used to model the relationship between two variables, such as the relationship between the cost of a product and the quantity produced. They can also be used to solve problems involving rates, such as the rate at which a car travels down a road.

In conclusion, equations in two variables, particularly linear equations, are essential tools in mathematics and various fields. They can be used to model relationships, solve problems, and make predictions. By understanding the basics of linear equations, we can apply them to a wide range of real-world situations and make informed decisions.

Description

Learn about linear equations in two variables and how to solve them using the slope-intercept form. Explore the applications of linear equations in various fields like physics, engineering, and economics. Understand the steps involved in solving linear equations and how they can be graphed to determine the domain and range of the variables.