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6.5 Graphing Linear Inequalities. Graphing Linear Equations. A linear equation can be written in either slope-intercept form Or in standard form To graph we find the y-intercept then apply the slope. Graphing Inequalities.
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Graphing Linear Equations • A linear equation can be written in either slope-intercept form • Or in standard form • To graph we find the y-intercept then apply the slope
Graphing Inequalities • Inequalities are graphed by figuring where the solution starts and using an arrow to indicate the solution region -4 -3 -2 -1 0 1 2 3 4 -4 -3 -2 -1 0 1 2 3 4
Equations The solutions to a linear equation are the ordered pairs (x,y) which make the equation… TRUE The point ( 1, 2) is a solution to the equation Inequalities So The solutions to a linear inequality are the ordered pairs (x,y) which make the inequality… TRUE Linear Inequalities
Solutions to Linear Inequalities Which ordered pairs make the inequality true? (0, 1) (1, 0) (10, -9) (-9, 10) In fact all of the points on the line make the inequality true. But what about points like… (3, 4), (0, 5) (-5, 8) (8, 9) (7, -4)
Solutions to Linear Inequalities (cont.) • We can replace the points that form the boundary line with a line • And we can replace all of the points in the region above the line with a shaded region • The graph of the line with a shaded region represents the graphical solution to the linear inequality above.
Graphing < or > Inequalities • If we have an inequality with a > or < symbol we have to adjust the graph • Just like on the number line if we want to indicate that the solution gets as close as possible but does not include a point we use an open circle • Since we are using a line instead of a point to represent the boundary we use a dotted line • The shaded region remains the same
Which Side to Shade? • Graph the line which represents the boundary of the inequality • Pick a test point to insert into the equation (usually the origin (0,0) if it is not on the line) • If the point makes the inequality TRUE shade the side which includes the point • If the points makes the inequality FALSE then shade the side that does not include the point • In this case Is true so shade the side with the test point
Graph the Linear Inequalities Pick (0, 0) as the test point