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Math Help - Need help on a problem *Urgent* please help

  1. #1
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    Need help on a problem *Urgent* please help

    Can anyone answer and explain the question: Find the intervals on which x satisfies x2+8x>0
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  2. #2
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    Re: Need help on a problem *Urgent* please help

    Factor out x and use the fact that the product is positive iff both factors have the same sign.
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  3. #3
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    Re: Need help on a problem *Urgent* please help

    Is this the right answer? im unsure of what the correct answer format is

    x<-8 makes expression positive
    -8<x<0 makes expression negative
    0<x makes expression positive
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  4. #4
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    Re: Need help on a problem *Urgent* please help

    Quote Originally Posted by emakarov View Post
    Factor out x and use the fact that the product is positive iff both factors have the same sign.
    Is this the right answer? im unsure of what the correct answer format is

    x<-8 makes expression positive
    -8<x<0 makes expression negative
    0<x makes expression positive
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  5. #5
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    Re: Need help on a problem *Urgent* please help

    Yes, this is the right answer. Since you only need to find when x2 + 8x > 0, the answer is x < -8 or x > 0. Alternatively, written as a union of intervals, x ∈ (-∞, -8) ∪ (0, ∞).
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  6. #6
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    Re: Need help on a problem *Urgent* please help

    Thanks very informative and helpful!
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