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Homework Help: 2nd order d.e

  1. Aug 30, 2008 #1
    1. The problem statement, all variables and given/known data
    x"=(-1/x^2) when x=c1>0 and x'=c2 at t=0 what relationship has to exist between c1 and c2 to give the problem a solution of k(t+B)^a.... then solve for k,a,B....

    3. The attempt at a solution
    x"+(1/x^2)=0, im sorry im just stuck, i think it goin to look somthin like (x+2)^2.... but this inverse square is confusing me... we normally do it like,

    [tex]\lambda[/tex]"+a[tex]\lambda[/tex]=0, but im not sure, can anyone plz point me in the right direction.... but then wat does it mean by what relationship between c1and c2?
  2. jcsd
  3. Aug 31, 2008 #2


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    Science Advisor

    The first thing you need to do is state the problem clearly. " x"= -1/x2 when x= c1> 0" only gives x" at a single value of x. Did you mean "for x> c1"?

    Rewrite the equation as x2x"= -x and see what happens when you replace x with k(t+B)a.
  4. Aug 31, 2008 #3
    na thats wat the question says... its definately x=c1>0..... huh i cant write it like that coz then it would be (x^2)x"=-1 not -x.... wel doesnt that mean that c1=c2???
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