Question 1047682
Can you explain how to to solve this problem? 
n=x
∑ = n^2-2n+1=630
n=12
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If n = 12 , n^2-2n+1 = 144-24+1 = 121 = 11^2
If n = 13, n^2-2n+1 = 169-26+1 = 144 = 12^2
If n = 14, n^2-2n+1 = 196-28+1 = 169 = 13^2
If n = 15, 14^2 = 196
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Add those to get 690

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Ans: x = 15
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Cheers,
Stan H.
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