Math

Find all real numbers x such that x^2 -8>0. Write your final answer in interval notation.

I really just need a starter step. I remember these questions, but I'm not sure how to start. Please help!

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asked by Anonymous

  1. x^2 - 8 > 0
    x^2 > 8

    That should help.

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    posted by Steve

  2. So the sign is flipped because we moved a negative number, right?

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    posted by Anonymous

  3. no, you can add and subtract anything without flipping the direction. Only if you multiply or divide by a negative value does the direction change.

    It's really just a shortcut to moving things to the other side:

    -2x < 8
    0 < 8+2x
    -8 < 2x
    -4 < x

    That's the same as dividing and flipping at once:

    -2x < 8
    x > -4

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    posted by Steve

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