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Factoring vs. original equation

  1. Jan 12, 2010 #1
    ok so i was presented with the equation x^2-7x+12=0 and i cant decide what the answer should be. if i factor the equation i come up with 3 and 4. but when i plug those back into the original equation it doesnt work. so does that mean that there is no answer or does it mean i'm doing something wrong?
     
  2. jcsd
  3. Jan 12, 2010 #2

    Mentallic

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    It means you're calculating the values you plugged back into the equation incorrectly :tongue:

    3 and 4 are the correct answers, so try plugging them in once more, and if you still aren't getting zero after plugging in those values, post what you've done so we can help show you what you've done wrong (even if you used a calculator, show us exactly how you wrote it in the calculator because the misuse of brackets can screw up a lot of people).
     
  4. Jan 12, 2010 #3
    well now i feel like a dummy
     
  5. Jan 12, 2010 #4

    Mentallic

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    Happens all the time :smile: - but... you don't... do it all the time do you?

    Haha good luck with those quadratics :wink:
     
  6. Jan 12, 2010 #5
    Um. You mean -3 and -4.
     
  7. Jan 12, 2010 #6

    Mentallic

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    Phrak, best you go back and revise your quadratics as well :tongue:
     
  8. Jan 13, 2010 #7

    Mark44

    Staff: Mentor

    I agree. The OP arrived at the correct solutions, but made a mistake in checking them.
     
  9. Jan 16, 2010 #8
    Oh my! You got me.
     
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