The Slope of the Line y=mx+b
- Slope of a Line – Definition
- Understanding Slope as a Rate of Change
- Different Types of Slope
- Finding the Slope on a Graph – Step-By-Step Instructions and Examples
- Finding the Slope When Given Two Points – Step-by-Step Instructions
- Finding the Slope from an Equation
- The Slope of a Line – Practice Questions
- The Slope of a Line – Summary
- The Slope of a Line – Frequently Asked Questions

Then why not use our learning videos, and practice for school with learning games.
Try for 30 DaysLearning text on the topic The Slope of the Line y=mx+b
Slope of a Line – Definition
In everyday life, we encounter slopes from the steepness of a hill to the angle of a ramp. In mathematics, the slope of a line measures how steep a line is. It is often also referred to as the gradient.
The slope represents the steepness or incline of a line, defined as the ratio of the vertical change (rise) to the horizontal change (run) between two points on the line.
Understanding Slope as a Rate of Change
The slope of a line is a measure of how one variable changes in relation to another. It's the same as a rate of change you might encounter in everyday life, such as speed.
The slope of a line can be an integer (whole number) or a fraction or decimal too. It can be positive to represent a line going upwards from left to right, or negative indicating a line that goes down from left to right. It is given by the value of in the equation of a straight line, .
For example, imagine you're on a road trip and want to calculate the average speed of your journey. Speed is a rate of change - it reflects how distance changes over time. In this case, the slope (speed) is the change in distance (rise) divided by the change in time (run).
Graphing the Data:
- Plot these points on a graph with 'Time' on the -axis and 'Distance' on the -axis.
Finding the Slope (Speed):
- Choose any two points on the graph. For example, and .
- Apply the slope formula: Slope (Speed) = () = ()
- Slope (Speed) = miles per hour.
Equation of the Line:
- The equation representing this relationship in the form could be written as Distance = .
- This equation tells us that for every hour of travel, the distance increases by 50 miles.
Understanding the concept of slope as a unit rate, like speed, helps make connections between mathematical concepts and real-world scenarios. It demonstrates how slope is not just a theoretical idea but a practical tool for everyday calculations.
Different Types of Slope
Type Of Slope | Description | Graph | Example |
---|---|---|---|
Positive Slope | Rises to the right, indicating the slope value is a positive number. As you move from left to right, the line goes up. | |
|
Negative Slope | Falls to the right, indicating the slope value is a negative number. As you move from left to right, the line goes down. | |
|
Zero Slope | Represents a horizontal line, indicating the slope value is zero. There's no rise over the run. | |
|
Undefined Slope | Represents a vertical line, indicating the slope is undefined because division by zero is not possible in mathematics. | |
Slope is undefined |
Finding the Slope on a Graph – Step-By-Step Instructions and Examples
When looking at a graph, the slope () is determined by how much the line rises (goes up or down) for every unit it runs (moves right). This can be visually represented and calculated as .
Step | Description | Visual |
---|---|---|
Identify Points | Locate the points on the graph. For this example, the points are and . | |
Rise and Run | Observe the rise and run between the points. From to is a rise of 3 units (upwards), and from to is a run of 2 units (to the right). | |
Slope Calculation | Calculate the slope using the rise over run. The slope , indicating the line rises 3 units for every 2 units it moves to the right. | |
Find the slope of the graphs.
Finding the Slope When Given Two Points – Step-by-Step Instructions
To calculate the slope, use the formula when you know at least two points on the line. This formula makes it easy to see how steep a line is without a protractor.
What is the slope of the line that passes through the points and ?
To calculate the slope of a line given two points, and , we use the slope formula:
Step 1: Identify the coordinates of the two points.
Point 1: , where and
Point 2: , where and
Step 2: Plug the coordinates into the slope formula.
It is important to do the calculation in the correct order as mixing up the positions of the and values in the formula can result in different answers to the one we want!
Step 3: Perform the subtraction in the numerator and the denominator.
Step 4: Simplify the fraction.
Therefore, the slope of the line passing through the points and is .
This negative slope indicates that the line falls as it moves from left to right.
Try some on your own!
Computing the slope of a line can be useful when analysing data and identifying patterns.
Finding the Slope from an Equation
Understanding how to find the slope from an equation involves recognising the slope-intercept form of a line, which is expressed as . In this form, represents the slope of the line, indicating how steep it is and in which direction it tilts. The value represents the y-intercept, where the line crosses the y-axis.
The slope-intercept form provides a straightforward way to identify the slope directly from the equation of a line. The coefficient of (that is, ) is the slope. This tells us by how many units changes for every one-unit increase in .
Consider the equation of a line .
Identify the Slope: In the equation , the coefficient of is . This means the slope () of the line is .
Interpret the Slope: A slope of means that for every one unit the value increases, the value increases by units. This indicates the line rises to the right.
The Slope of a Line – Practice Questions
The Slope of a Line – Summary
Key Learnings from this Text:
The slope of a line tells us how steep it is by comparing the vertical change to the horizontal change between two points.
Slope is directly related to the rate of change, similar to everyday concepts like speed. It shows how quickly one thing changes in relation to another.
You can find the slope by using the formula , which helps us understand the line's incline without needing any special tools.
By looking at a graph, we can visually determine the slope by identifying the rise and run between two points. This visual approach makes it easier to understand the concept of slope.
Understanding slope is crucial for solving real-life problems, from designing ramps to calculating how fast an object moves. It's a practical skill that connects classroom math to the world around us.
Having a solid understanding of the slope of a line will be helpful with graphing linear equations, and solving systems of equations by graphing.