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Math Help - solve the inequality x^2+2x<3

  1. #1
    Junior Member
    Joined
    Oct 2008
    Posts
    50

    solve the inequality x^2+2x<3

    i have the answer but i m not enitirely sure how i got it... can somebody explain how this is done?

    revising for As exam tomorrow and panicing lol

    thanks!
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  2. #2
    MHF Contributor
    Joined
    Nov 2008
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    France
    Posts
    1,458
    Hi

    Inequation x^2 + 2x < 3 is equivalent to x^2 + 2x - 3 < 0

    1 is solution of x^2 + 2x - 3 = 0 therefore you can factor by (x-1)

    (x-1)(x+3) < 0

    A product of 2 factors is negative when exactly one of them is negative and the other one positive
    Review all the possible cases, build a table of signs to find the answer
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