Tuesday, October 18, 2011

10-18 Graping an absolute value inequality

Homework for Wednesday and Thursday is to do review problems, page 59, 60, 61;
Items 7 through 49 odds.  Do the work on a separate sheet with your name on it, and hand it in Thursday.

Today bell-ringer and inclass:  Solve and graph |x-3| < 2

When a problem has absolute value bars |  |, you need to remove them and follow the rules for solving two parts of the problem.

Remove the absolute value bars and write what's left twice:

x-3 < 2        x-3 < 2

One of these is the original and you leave it alone.  For the other, introduce a negative sign (to create the opposite) AND change the direction of the inequality:

(original)   x-3 < 2                                      (opposite)   x-3 > -2

add 3 to each side                                      add 3 to each side
x < 5                                                          x > 1
position is 5                                                position is 1
dot is closed                                               dot is closed
thick arrow points left                                 thick arrow points right

Combine the graphs into one segment from 1 to 5 where the arrow tails overlap.


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