Solving inequalities analytically?

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#66

From: Peter Brewer
Date: Tue, 29 Sep 1998 00:00

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Consider this inequality:
    x^2 +2x -3 > 0
Which factorises to:
    (x+3)(x-1) > 0
The natural thing to say is therefore
     x > -3 and x > 1
However, if this inequality is solved graphically then the solution is
    x < -3 and x > 1
which I believe is the correct answer. Can anyone tell me why the first
technique is invalid?

    Thanks in advance,
            Pete

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From: "Peter Brewer" <Peter@darkpit.demon.co.uk>
Subject: Solving inequalities analytically?
Date: 1998/09/29
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