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Homework Help: High school calc problem

  1. Jan 28, 2008 #1
    [SOLVED] high school calc problem

    1. The problem statement, all variables and given/known data
    If an object moves along the y axis (marked in feet) so that its position at time x (in seconds) is given by the indicated function; y= (x^3)-(9x^2)+15x;
    Find when v=0

    2. Relevant equations
    v=y prime, and i already have found y prime to be (3x^2)-(18x)+15

    3. The attempt at a solution
    I checked the selected answers in the back of the book and did a little plug and chug and called it a day...:blushing:.. haha. I'm assuming theres a more relevant process so any help is mucho appreciated. thanks.
  2. jcsd
  3. Jan 28, 2008 #2


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    Homework Helper

    if v=y'

    then shouldn't [itex]v=3x^2-18x+15 [/itex]

    when v=0

    [itex]3x^2-18x+15=0 [/itex]

    try some factorisation
  4. Jan 28, 2008 #3
    wow...thank you

    haha im not sure how i didn't see that. I really didn't think anyone would answer. I believe I've just found a new home for homework help....and considering I will be going into chemE next next year in college, I should be revisiting many of times!

    haha thank you a lot!
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