1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Help with curve equation

  1. Aug 12, 2010 #1
    A curve equation is y = 3x - x^3/2

    find the value of X when y=0

    please help me i don't know how to proceed..!!!!!!
     
  2. jcsd
  3. Aug 12, 2010 #2

    thrill3rnit3

    User Avatar
    Gold Member

    Re: Helpp(urgent)

    0 = 3x - x3/2
    x3/2 = 3x

    tell me if you still need help after that
     
  4. Aug 13, 2010 #3
    Re: Helpp(urgent)


    Yes infact its there that i am stuck..!!!!!!
     
  5. Aug 13, 2010 #4
    Re: Helpp(urgent)

    i want to know how to find the value of x
     
  6. Aug 13, 2010 #5

    berkeman

    User Avatar

    Staff: Mentor

    Re: Helpp(urgent)

    x3/2 = 3x

    [STRIKE]Hint -- remember that in working with equations, you want to do the SAME thing to both sides of the equation, while working to simplify everything. What operation can you do to both sides of this equation to get rid of an x on both sides....?[/STRIKE]

    EDIT -- oops, see better hint later by Mark44
     
    Last edited: Aug 13, 2010
  7. Aug 13, 2010 #6

    thrill3rnit3

    User Avatar
    Gold Member

    Re: Helpp(urgent)

    Don't forget the case x=0 though.
     
  8. Aug 13, 2010 #7

    Mark44

    Staff: Mentor

    Re: Helpp(urgent)

    Writing the equation as x3/2 = 3x is NOT a good strategy. Instead, work with x3 - 6x = 0 (equivalent to the one you started with) and factor the cubic expression.
     
  9. Aug 13, 2010 #8

    thrill3rnit3

    User Avatar
    Gold Member

    Re: Helpp(urgent)

    They both yield the same answers, except that you lose the solution x=0 if you do the first method. I'm sorry if I forgot to make that clear.
     
  10. Aug 13, 2010 #9

    Mark44

    Staff: Mentor

    Re: Helpp(urgent)

    That's why factoring is a better strategy - you don't lose solutions.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook