Find the sum of all real roots of the equation above.
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As this is a product, it will equal zero when at least of of the factors is zero. Therefore, we set the term inside the product equal to zero.
( x + k ) k − 1 ( x − k ) k + 1 = 0 ( x − k ) k + 1 = 0 x − k = 0 x = k
Where k varies among the integers from 1 to 63. To find the sum of the roots, we sum all k's.
k = 1 ∑ 6 3 k
Using the formula for the sum of the first n integers, we have
k = 1 ∑ 6 3 k = 2 6 3 ⋅ 6 4
Evaluating, we get 2 0 1 6