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it-is-given-that-1-n-r-1-n-x-r-2-and-1-n-r-1-n-x-r-2-1-n-2-r-1-n-2-3-determine-in-terms-of-n-the-value-of-r-1-n-x-r-1-2-




Question Number 33152 by Rio Mike last updated on 11/Apr/18
it is given that  (1/n)Σ_(r=1) ^n  x^r =2 and (√((1/n)Σ_(r=1) ^n (x_r )^2 −(1/n^2 )(Σ_(r=1) ^n )^2 ))= 3  determine in terms of n the value  of.  Σ_(r=1) ^n (x_r +1)^2
itisgiventhat1nnr=1xr=2and1nnr=1(xr)21n2(nr=1)2=3determineintermsofnthevalueof.nr=1(xr+1)2
Commented by prof Abdo imad last updated on 12/Apr/18
we have  Σ_(r=1) ^n  x^r  =2n  ,(1/n) Σ_(r=1) ^n  x_r ^2   −1=9  because (Σ 1)^2  =n^2  ⇒  Σ_(r=1) ^n x_r ^2   =10n so  Σ_(r=1) ^n  (x_r  +1)^2  = Σ_(r=1) ^n  ( x_r ^2  +2x_r  +1)  = Σ_(r=1) ^n   x_r ^2   + 2 Σ_(r=1) ^n  x_r   + n  =10n +4n  +n  =15n  (  if there is no mistake in  the question)
wehaver=1nxr=2n,1nr=1nxr21=9because(Σ1)2=n2r=1nxr2=10nsor=1n(xr+1)2=r=1n(xr2+2xr+1)=r=1nxr2+2r=1nxr+n=10n+4n+n=15n(ifthereisnomistakeinthequestion)

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