Mathematics
Grade 8
15 min
Identify the graph of an equation
Identify the graph of an equation
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Interpret the slope and y-intercept from a linear equation.
Create a table of values for a given linear equation.
Plot ordered pairs accurately on a coordinate plane.
Match a linear equation to its corresponding graph.
Identify the equation that represents a given linear graph.
Distinguish between graphs of linear and simple non-linear equations (e.g., $y=x^2$).
Verify if a given point lies on the graph of an equation.
Ever wondered how mathematicians can predict the path of a rocket or the growth of a plant? 🚀🌱 It all starts with understanding how equations draw pictures!
In this lesson, you'll learn how to connect algebraic equations to their visual representations on a graph. This skill is fundamental for understanding relationships between q...
2
Key Concepts & Vocabulary
TermDefinitionExample
Coordinate PlaneA two-dimensional surface formed by the intersection of a horizontal number line (x-axis) and a vertical number line (y-axis). It's used to plot points.Imagine a city map where streets run east-west (x-axis) and north-south (y-axis); any location is a point on this plane.
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.The point $(3, -2)$ means move 3 units right from the origin and 2 units down.
Linear EquationAn equation whose graph is a straight line. It can often be written in the form $y = mx + b$.$y = 2x + 1$ is a linear equation because its graph is a straight line.
Slope (m)A measure of the steepness and...
3
Core Formulas
Slope-Intercept Form of a Linear Equation
$y = mx + b$
This form directly shows the slope ($m$) and the y-intercept ($b$) of a linear equation. 'm' tells you how steep the line is and its direction (up/down from left to right), and 'b' tells you where the line crosses the y-axis.
Slope Formula
$m = rac{y_2 - y_1}{x_2 - x_1}$
Use this formula to calculate the slope ($m$) of a line if you are given any two distinct points $(x_1, y_1)$ and $(x_2, y_2)$ on the line. This is useful for finding the equation from a graph.
Point Verification Rule
If a point $(x, y)$ lies on the graph of an equation, then substituting its coordinates into the equation must make the equation true.
To check if a graph matches an equation, pick a few points from the graph an...
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Challenging
A line passes through the point (-2, 6) and has a slope of -4. What is the y-intercept of this line?
A.6
B.8
C.-2
D.14
Challenging
The graph of y = mx + b passes through Quadrant II and Quadrant IV, but not Quadrant I. What must be true about the values of m and b?
A.m < 0 and b can be any value
B.m < 0 and b < 0
C.m > 0 and b < 0
D.m < 0 and b > 0
Challenging
The line 2x + Ay = 8 passes through the point (2, 1). Which of the following equations represents the same line?
A.y = 2x + 5
B.y = -2x + 5
C.y = 4x + 3
D.y = -4x + 10
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