Linear Equations and Graphs — Grade 8 Math Study Guide
What is a Linear Equation?
● A linear equation is an equation that makes a straight line when you draw it on a graph.
● The general form is:
y = m x + c
where:
○ m is the slope (how steep the line is)
○ c is the y-intercept (where the line crosses the y-axis)
Understanding the Slope (m)
● The slope shows how y changes when x changes.
● You find it by:
slope (m) = change in y ÷ change in x
● If m > 0, the line goes up.
● If m < 0, the line goes down.
● If m = 0, the line is flat (horizontal).
● If m is undefined, the line is vertical.
Understanding the Y-Intercept (c)
● The y-intercept is the value of y when x = 0.
● It shows where the line crosses the y-axis (the vertical line on the graph).
What is a Linear Equation?
● A linear equation is an equation that makes a straight line when you draw it on a graph.
● The general form is:
y = m x + c
where:
○ m is the slope (how steep the line is)
○ c is the y-intercept (where the line crosses the y-axis)
Understanding the Slope (m)
● The slope shows how y changes when x changes.
● You find it by:
slope (m) = change in y ÷ change in x
● If m > 0, the line goes up.
● If m < 0, the line goes down.
● If m = 0, the line is flat (horizontal).
● If m is undefined, the line is vertical.
Understanding the Y-Intercept (c)
● The y-intercept is the value of y when x = 0.
● It shows where the line crosses the y-axis (the vertical line on the graph).
