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C3 - Differentiation Watch

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    Okay.. this has popped up quite a few times. I've simplified and simplified to get \frac{dy}{dx}=\frac{2\sqrt{4}}{5  }. Now, my understanding is that the answer is + or - 0.8, however, whenever I get a square root in a differential equation, they always only list the positive answer. Am I wrong in saying that dy/dx has two values here?
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    (Original post by ViralRiver)
    Okay.. this has popped up quite a few times. I've simplified and simplified to get \frac{dy}{dx}=\frac{2\sqrt{4}}{5  }. Now, my understanding is that the answer is + or - 0.8, however, whenever I get a square root in a differential equation, they always only list the positive answer. Am I wrong in saying that dy/dx has two values here?
     \sqrt is defined as the positive square root, so only the positive answer is given. You only really get  \pm in things like  x^2 = 4 , etc.
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    So would saying x^2=4\Rightarrow x=\sqrt{4} be incorrect?
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    (Original post by ViralRiver)
    So would saying x^2=4\Rightarrow x=\sqrt{4} be incorrect?
    Kind of. It's more x^2=4\Rightarrow x= \pm\sqrt{4}

    EDIT: Square roots (beginning of 3rd paragraph)
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    Okay, thanks a lot .

    I'd +rep but I'm out >< .
 
 
 
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