What Is a Linear Equation?

A linear equation is an equation with two variables (x and y). It shows a straight line when plotted on a graph. Here is an example of a linear equation:

linear equations linear equation example Here is this linear equation plotted on a graph:

linear equations linear equation graph

Linear Equation Curriculum

All the lessons on this page are related to linear equations. They are grouped into mini-curriculums (or curricula if you prefer the Latin plural) to help you organise your learning. A brief description is given for each mini-curriculum. Click the MORE button for an overview of the topic and for the links to the specific lessons and tests.

We Have Widgets!

Many of our lessons feature widgets like the one below. This widget lets you create your own graph and download it as an image, which – if you're a tutor – you might find useful for creating worksheets.

Create your own linear equation!

Change the Equation
y
x
y-intercept
Take a multiple-choice test on linear equations.

Equations and Linear Equations

linear equations about linear equations

Equations show that two mathematical expressions are equal to each other. Linear equations are the simplest type of equation and show straight lines when plotted. In this mini-curriculum, you will learn about equations and linear equations.

Equation
An equation tells us that two things are equal. Equality is denoted by the equals sign (=).
Here is an example of an equation:
linear equations equation

It tells us that x is equal to 2. Equations can show the relationships between combinations of letters and numbers.

Linear Equation
A linear equation is an equation that shows a straight line when it is plotted on a graph.
Here is an example of a linear equation and the line it shows when plotted on a graph:
linear equations linear equation

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equations
linear equations

Lines, Slope and Y-Intercept

linear equations lines slopes y-intercepts

Linear equations can be written in different forms. The slope-intercept form of a linear equation lets us read off what the slope and y-intercept of a line are. In this mini-curriculum, you will learn what the slope and y-intercept of a line are and how you can read them off from a linear equation.

Linear Equation in Slope-Intercept Form
A linear equation in slope-intercept form is written as y = mx + c, where m is the slope and c is the y-intercept.
Here is an example of a linear equation in slope-intercept form and the line it shows when plotted on a graph:
linear equations slope-intercept_form

- The slope is 2 because this is the number in front of the x.
- The y-intercept is 1 because this is the number added after the x.

Slope
The slope of a line is its steepness. The larger the slope, the steeper the line.
linear equations slope

Find Slope from Line
To find the slope of a line, divide how far up the line goes by how far across the line goes.
Here is an example of a line with a slope of 1. It goes up 4 units and goes across 4 units, so its slope is (4 ÷ 4 = ) 1.
linear equations find slope of line

Find Slope from Linear Equation
To find the slope of a line from a linear equation, look at the number in front of the x.
Here is a linear equation that shows a line with a slope of 2 because there is a 2 in front of the x:


Y-Intercept
The y-intercept is the y-coordinate of the point where a line crosses the y-axis.
linear equations y-intercept

Find Y-Intercept from Line
To find the y-intercept of a line, read off the y-coordinate of where the line crosses the y-axis.
Here is an example of a line with a y-intercept of 1.
linear equations find y-intercept_of_line

Find Y-Intercept from Linear Equation

To find the y-intercept of a line from a linear equation, look at the constant term (that is not in front of x or y).
Here is a linear equation that shows a line with a y-intercept of 1 because 1 is the constant term:
linear equations find y-intercept_from_linear_equation

Find Equation of a Line
To find the equation of a line, find the slope and write it in front of the x and find the y-intercept and write it as the constant.
A line with a slope of 2 and a y-intercept of 1 will have an equation of:

y = 2x + 1

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linear equations in slope-intercept form
slope
how to find the slope of a line
how to find the slope from a linear equation
the y-intercept
how to find the y-intercept of a line
how to find the y-intercept from a linear equation
how to find the equation of a line

Slope-Point Form

linear equations about slope-point_form

Linear equations can be written in different forms. The slope-point form of a linear equation lets us read off what the slope of a line is and the Cartesian coordinates of a point the line passes through. In this mini-curriculum, you will learn about the slope-point form of a linear equation.

Slope-Point Form
A linear equation in slope-point form is written as y − y1 = m(x − x1), where m is the slope and (x1, y1) are the Cartesian coordinates of a point on the line.
Here is an example of a linear equation in slope-point form and the line it shows when plotted on a graph:
linear equations slope-point_form

- The slope is 2 because this is the number in front of the brackets.
- The line passes through the point with Cartesian coordinates (1, 3) because of the numbers after the − signs

Find Slope from Linear Equation in Slope-Point Form
To find the slope of a line from a linear equation in slope-point form, look at the number in front of the brackets.
linear equations find slope from linear equation slope-point

Find Y-Intercept from Linear Equation in Slope-Point Form
To find the y-intercept of a line from a linear equation in slope-point form, substitute x = 0 into the equation and rearrange it.

y − 3 = 2(x − 1)
y − 3 = 2(0 − 1) ⇒ y = 1

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linear equations in slope-point form
how to find the slope from a linear equation in slope-point form
how to find the y-intercept from a linear equation in slope-point form

General Form

linear equations about general form

Linear equations can be written in different forms. The general form of a linear equation does not let us read off anything about the line it represents. In this mini-curriculum, you will learn about the general form of a linear equation.

General Form
A linear equation in general form is written as ax + by + c = 0.
Here is an example of a linear equation in general form and the line it shows when plotted on a graph:
linear equations general form

Find Slope from Linear Equation in General Form
The slope of a line can be found from a linear equation in general form.
linear equations find slope from linear equation general

Find Y-Intercept from Linear Equation in General Form

The y-intercept of a line can be found from a linear equation in general form.
linear equations find y-intercept_from_linear_equation_general

Convert General Form to Slope-Intercept Form
A linear equation in general form can be converted to slope-intercept form.
linear equations convert general to slope intercept form

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linear equations in general form
how to find the slope from a linear equation in general form
how to find the y-intercept from a linear equation in general form
how to convert a linear equation from general to slope-intercept form

Equation of a Line Between Two Points

linear equations about equation of line between two points

If we know the Cartesian coordinates of two points on a line, the equation of the line can be found. In this mini-curriculum, you will learn about how to find the linear equation of a line between two points.

Find Equation of Line Between Two Points
The equation of a line where (x1, y1) and (x2, y2) are the Cartesian coordinates of two points on the line is:
linear equations equation of line between two points

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how to find the equation of a line between two points