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Differentials - not understanding directions

  1. Jan 10, 2010 #1
    1. The problem statement, all variables and given/known data
    Find dy and evaluate dy for the given value x and dx

    y = x^3 - 3x, x = 2, dx = 0.05

    2. Relevant equations

    3. The attempt at a solution
    I have no idea how to begin this problem.
    I assumed that I find y'.
    Then plug in x into y'.
    Following that, I am not sure.
  2. jcsd
  3. Jan 10, 2010 #2


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    [tex]\mathrm{d}y = \frac{\mathrm{d}y}{\mathrm{d}x}\mathrm{d}x = y'\,\mathrm{d}x[/tex]
  4. Jan 10, 2010 #3
    Thank you, that was straight forward.
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