SOLUTION: show that sum of (xi-a)^2=sum of (xi-x bar)^2+n(x bar -a)^2

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Question 1121817: show that sum of (xi-a)^2=sum of (xi-x bar)^2+n(x bar -a)^2
Answer by Alex.33(110) About Me  (Show Source):
You can put this solution on YOUR website!
x bar=X.
3.SUM[(xi-a)^2]=SUM[xi^2]+na^2-2a*(SUM[xi])=SUM[xi^2]+na^2-2anX
1.SUM[(xi-X)^2]=SUM[xi^2]+nX^2-2X*SUM[xi]=SUM[xi^2]+nX^2-2nX^2=SUM[xi^2]-nX^2
2.n(X-a)^2=nX^2+na^2-2anX.
1+2=3. Done.