SOLUTION: x^2-9<0 solve the inequality.

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Question 59405: x^2-9<0
solve the inequality.
Answer by funmath(2933) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2-9%3C0
solve the inequality.
Find the numbers that make the equation equal 0.
%28x%2B3%29%28x-3%29=0
x+3=0 and x-3=0
x+3-3=0-3 and x-3+3=0+3
x=-3 and x=3
Now you test the intervals (-infinity,-3), (-3,3), (3,infinity)
By plugging in a test number of your choice in each number, if the result is less than 0 (negative) the interval is part of the solution.
For (-infinity,-3) test -4
%28-4%29%5E2-9
16-9
7 7 is greater tahn 0 (positive), so the interval is not included.
For (-3,3) test 0
%280%29%5E2-9
0-9
-9 -9 is less than 0 (negative), so (-3,3) is part of the solution.
For (3,infinity) test 4
%284%29%5E2-9
16-9
7 is greater than 0 (positive), so (3,infinity) is not part of the solution.
The soltuion is (-3,3) in interval notation
-3%3Cx%3C3 is also a notation commonly used.
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Notice that if the inequality was x%5E2-9%3E0, the soltuion would have been (-infinity,-3)U(3,infinity). Think about it and fun with it.
Happy Calculating!!!