Big Ideas Math: Modeling Real Life, Grade 8
BI
Big Ideas Math: Modeling Real Life, Grade 8 View details
5. Graphing Linear Equations in Standard Form
Continue to next subchapter

Exercise 11 Page 169

What information can you learn from the slope-intercept form of an equation?

Practice makes perfect
Equations written in slope-intercept form follow a specific format. y= mx+ b In this form, m represents the slope of the line and b represents the y-intercept.

Identifying the Slope and y-intercept

Since the given equation is not in slope-intercept form, let's rewrite it so that it will be easier to identify the slope and y-intercept.
4x+y=5
4x+y-4x=5-4x
y=5-4x
y=-4x+5
Below we have highlighted the slope m and y-intercept b. y= -4x+ 5 The slope is -4. The y-intercept is 5, so the graph crosses the y-axis at the point (0, 5).

Graphing the Equation

A slope of -4 means that for every 1 unit we move in the positive horizontal direction, we move 4 units in the negative vertical direction. m= -4/1 ⇔ rise/run=-4/1 To graph the equation, plot the y-intercept and then use the slope to find another point on the line.