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Homework Help: Use DE to show error percentage

  1. Nov 4, 2013 #1
    1. The problem statement, all variables and given/known data
    Use Differentials to show that an error of 2% in the measurement of the side of a square results in an error of approximately 4% in the calculation of the area

    2. Relevant equations

    I'm using Area =(sΔx)^2

    3. The attempt at a solution
    Using Δx=0.02,
    Area= [itex]s^{2}[/itex][itex]0.02^{2}[/itex] =[itex]s^{2}[/itex]/2500=0.04%[itex]\times[/itex][itex]s^{2}[/itex]
  2. jcsd
  3. Nov 4, 2013 #2


    Staff: Mentor

    This is incorrect. The formula for area is A = s2. The differential of the area would be dA = (dA/ds) * ds ≈ dA/ds * Δs.

    Don't confuse yourself by using two variables for the length of a side of the square. You shouldn't have both s and Δx in your work.
  4. Nov 4, 2013 #3

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    Do you really not know the difference between 4% and .04% ?
  5. Nov 8, 2013 #4
    i know... i got it wrong... hence i'm asking for help.
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