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1² +2²+3² +...+ (n − 1)² = |
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Answer» The sum of number squares can be worked out using the formula Σn = (2 x n ^3 + 3 x n ^ 2 + n)/6 So for sum of n = 1, Σn = (2 x 1^3 + 3 x 1 ^2 + 1) / 6 = 6 /6 = 1 Using this formula, I will work out the sum of all numbers up to 10. n = 1 , Σn = 1 n = 2, Σn = 5 n = 3, Σn = 14 n = 4, Σn =30 n = 5, Σn = 55 n = 6, Σn = 91 n = 7, Σn = 140 n = 8, Σn = 204 n = 9, Σn = 285 n = 10, Σn = 385 |
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