SOLUTION: Solve the inequality. (Enter your answer using interval notation.) |x| < 6

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Question 1184097: Solve the inequality. (Enter your answer using interval notation.)
|x| < 6

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


The absolute value inequality means x is between -6 and +6:

abs%28x%29%3C6 ==> -6%3Cx%3C6 ==> (-6,6)

It is helpful to solve absolute value inequalities by interpreting abs%28x-a%29%3Cb to mean "the distance between x and a is less than b".

Your example is then

abs%28x%29%3C6 ==> abs%28x-0%29%3C6 ==> the distance between x and 0 is less than 6.

That means x can be up to 6 units to the left of 0 or up to 6 units to the right of 0; and that gives the answer (-6,6).

Let's look at another slightly more complicated example using a formal algebraic solution and a solution using the interpretation of absolute value as the distance between points.

Solve abs%28x-4%29%3C3

(1) Algebraically....

"x-4 is between -3 and +3":

-3+%3C+x-4+%3C+3
-3%2B4+%3C+x+%3C+3%2B4
1+%3C+x+%3C+7

Solution: (1,7)

(2) Using distances....

"the distance between x and 4 is less than 3"

3 to the left of 4 is 1; 3 to the right is 7

Solution: (1,7)

The solutions by both methods are relatively simple. But for more complicated absolute value problems, using the interpretation of absolute value as the distance between points is usually easier.