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October 1st, 2010, 10:24 AM   #1
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functions

Given f(x) = |x - 7|, find all values of x such that f(x) > 6. Write your answer in interval notation.

I have done this problem several times, and I keep getting it wrong!
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October 1st, 2010, 10:38 AM   #2
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Re: functions

You need to find both:

(1) (x - 7) > 6

x > 13

(2) (x - 7) < - 6

x < 1

In interval notation:

(-?,1) U (13,?)
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October 1st, 2010, 01:20 PM   #3
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Re: functions

Quote:
Originally Posted by willab
Given f(x) = |x - 7|, find all values of x such that f(x) > 6. Write your answer in interval notation.

I have done this problem several times, and I keep getting it wrong!
An easy way is to find x so that f(x)?6, i.e. x is within 6 units of 7, giving [1,13] as that interval.
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