Mathematics Grade 8 15 min

Graph a line from an equation

Graph a line from an equation

Tutorial Preview

1

Introduction & Learning Objectives

Learning Objectives Identify the slope and y-intercept from a linear equation in slope-intercept form. Plot the y-intercept on a coordinate plane. Use the slope (rise over run) to find additional points on the line. Graph a linear equation by plotting at least two points and drawing a straight line through them. Rearrange a linear equation from standard form (Ax + By = C) into slope-intercept form (y = mx + b). Graph a linear equation by finding and plotting its x- and y-intercepts. Ever wonder how roller coasters are designed or how architects plan buildings? 🎢 Lines are everywhere, and understanding their equations helps us predict and create! In this lesson, you'll learn how to take a linear equation and visually represent it on a graph. This skill is fundamental f...
2

Key Concepts & Vocabulary

TermDefinitionExample Linear EquationAn equation whose graph is a straight line. It can be written in forms like y = mx + b or Ax + By = C.y = 2x + 3 Coordinate PlaneA two-dimensional plane formed by the intersection of a horizontal number line (x-axis) and a vertical number line (y-axis). Used for plotting points.The grid system where you plot points like (2, 5). Ordered PairA pair of numbers (x, y) that represents a single point on the coordinate plane, where x is the horizontal position and y is the vertical position.(3, -1) means 3 units right and 1 unit down from the origin. Slope (m)A measure of the steepness and direction of a line. It is calculated as 'rise over run' (change in y / change in x).In y = 2x + 3, the slope is m = 2, meaning for every 1 unit right, the line g...
3

Core Formulas

Slope-Intercept Form $y = mx + b$ This form directly shows the slope ($m$) and the y-intercept ($b$). To graph, plot the y-intercept $(0, b)$, then use the slope $\frac{\text{rise}}{\text{run}}$ to find a second point. Standard Form of a Linear Equation $Ax + By = C$ This form is useful for finding the x- and y-intercepts. To find the x-intercept, set $y=0$ and solve for $x$. To find the y-intercept, set $x=0$ and solve for $y$. Plot these two intercepts and draw the line. Slope Formula $m = \frac{y_2 - y_1}{x_2 - x_1}$ While not directly used to graph *from* an equation, this formula defines slope. Understanding it helps interpret $m$ in $y=mx+b$ as the change in y over the change in x between any two points $(x_1, y_1)$ and $(x_2, y_2)$ on the line.

5 more steps in this tutorial

Sign up free to access the complete tutorial with worked examples and practice.

Sign Up Free to Continue

Sample Practice Questions

Challenging
What is the slope of the line represented by the equation y = -5, and how would its graph appear?
A.The slope is -5, and the line goes down from left to right.
B.The slope is 0, and it is a horizontal line.
C.The slope is undefined, and it is a vertical line.
D.The slope is 1, and it passes through (0, -5).
Challenging
What is the slope of the line represented by the equation x = 3, and how would its graph appear?
A.The slope is 3, and the line is very steep.
B.The slope is 0, and it is a horizontal line.
C.The slope is undefined, and it is a vertical line.
D.The slope is 1, and it passes through (3, 3).
Challenging
You need to graph the equation 2x + 5y = 7. A classmate suggests rearranging to slope-intercept form is the best method. Why might they be correct?
A.Because finding the intercepts gives non-integer coordinates (3.5, 0) and (0, 1.4), which are hard to plot accurately.
B.Because the slope will be a whole number, making it easy to use.
C.Because the y-intercept will be a whole number, making it easy to plot.
D.Because the intercept method never works for an equation like this.

Want to practice and check your answers?

Sign up to access all questions with instant feedback, explanations, and progress tracking.

Start Practicing Free

More from Linear equations

Ready to find your learning gaps?

Take a free diagnostic test and get a personalized learning plan in minutes.