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Differentiate an equation

  1. Nov 13, 2011 #1


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    My friend came up with the following:
    [itex]2x=1 \Rightarrow \frac{d}{dx}(2x)=\frac{d}{dx}1 \Rightarrow 2=0[/itex]. Shamefully I do not see what's wrong with this reasoning!
    Can someone help me? :)
  2. jcsd
  3. Nov 13, 2011 #2


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    2x=1 is not an identity. It is only true for x = 1/2.
  4. Nov 13, 2011 #3


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    Thank you LcKurtz, that makes sense.
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