5x - 8y = 40
1. Make a table of arbitrary values:
x | y
4 |
2 |
-2 |
-4 |
Calculate the other variable values:
Fill in the table:
x | y
4 | -2.5
2 | -3.75
-2 | -6.25
-4 | -7.5
Plot the points:
Draw a line through them:
2. Get the equation in slope-intercept form y = mx+b
5x - 8y = 40
-8y = -5x + 40
y = 
x - 5
The slope is and the y-intercept is (0,-5)
Start at the y-intercept, draw a vertical line upward
5 units (the numerator of the slope), and from there
draw a horizontal line rightward 8 units (the denominator
of the slope):
Draw a line through the y-intercept (0,-5) and the end of the vertical
line:
3. Find the two intercepts
To find the x-intercept, we substitute 0 for y:
5x - 8y = 40
5x - 8(0) = 40
5x - 0 = 40
5x = 40
x = 8, so the x-intercept is (8,0)
To find the y-intercept, we substitute 0 for x:
5x - 8y = 40
5(0) - 8y = 40
0 - 8y = 40
-8y = 40
y = -5, so the y-intercept is (0,-5).
Plot the intercepts:
Draw a line through those two intercepts:
Edwin
