I need to know how to graph inequalities. I need to know just abot everything. From graphing an equation to shading.thanx!
Hi Janice,
Graphing lines can be accomplished by any of the following methods:
-
create a table of values by choosing values for x and working out the values for y. Plot the resulting points and join them with a straight line.
Ex. y = 2x - 1
x: -2, -1, 0, 1, 2
y: -5, -3, -1, 1, 3
Now plot (-2, -5), (-1, -3), (0, -1), (1, 1), and (2, 3) and join them with a straight line. -
find the x-intercept and y-intercept and join them with a straight line
Ex. 3x + 4y = 12
x-int: 3x = 12 y-int: 4y = 12
x = 4 y = 3
Plot (4, 0) Plot (0, 3)
Now join these 2 points to get the line. -
determine the slope and y-intercept of the line, plot the y-intercept and find a second point on the line by moving vertically and horizontally according to the rise/run of the slope.
Ex. y = 3x + 5 slope = 3 (or 3/1 in "rise over run" form), y-intercept = 5
Plot the point (0, 5).
Move up 3 units and to the right 1 unit from the y-intercept. Plot a second point here.
Now join these two points to get the line.
To graph a linear inequality, follow the following steps:
-
Replace the inequality sign with an equal sign and graph the resulting line.
- If the inequality is a greater than (>) or a less than (<) you will graph the line as a dotted line.
- If the inequality includes "or equal to" as in "greater than or equal to", you graph the line as a solid line.
-
Choose a point on one side of the line (not on the line!) and substitute the coordinates into the inequality you started with.
- If you get a true mathematical statement (like 4<9), then you want to shade the side of the line that contains the point you used to do the test.
- If you get a false mathematical statement (like 0>3), then you want to shade the side of the line that does not contain the point you used to do the test.
Hope this helps,
Leeanne