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Difference Quotient

  1. Jan 7, 2010 #1
    I took a placement test and blew it away. (I tested into calculus, best possible placement for this test.) Everything was rather simple except for this problem which I cannot seem to get right. Can someone show me where I'm going wrong here?


    1. The problem statement, all variables and given/known data
    Use x2+2 in the Difference Quotient.


    2. Relevant equations
    d55.gif


    3. The attempt at a solution
    (x+h)2+2-(x2+2)

    x2+xh+h2+2-x2-2

    [STRIKE]x2[/STRIKE]+xh+h2[STRIKE]+2[/STRIKE][STRIKE]-x2[/STRIKE][STRIKE]-2[/STRIKE]

    (xh+h2)/h

    (x[STRIKE]h[/STRIKE]+h[STRIKE]2[/STRIKE])/[STRIKE]h[/STRIKE]

    x+h

    This answer was not a given choice. Any ideas where I'm messing up?
    (I'm sure I making stupid mistake somewhere that I'm overlooking)
     
  2. jcsd
  3. Jan 7, 2010 #2
    There is an error in this line.
     
  4. Jan 7, 2010 #3

    Mark44

    Staff: Mentor

    More specifically, you expanded (x + h)2 incorrectly. Also, you should use = between an expression on one line and the one on the following line.
     
  5. Jan 7, 2010 #4
    ahh! okay....

    x2+2xh+h2+2-x2-2

    =

    [STRIKE]x2[/STRIKE]+2xh+h2[STRIKE]+2-x2-2[/STRIKE]

    =

    2xh+h2/h

    =

    2x[STRIKE]h[/STRIKE]+h[STRIKE]2[/STRIKE]/[STRIKE]h[/STRIKE]

    =

    2x+h

    That is the answer I chose since it was closest to my answer. You guys rock, thanks!
     
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