Summation of the sereis
Algebra
Level
3
If r is a positive integer and n = 4r − 2 then what is the sum of the series 1 + 1 − 1 − 1 + 1 + 1 − 1 − 1 + ⋯ to n terms?
The answer is 2.
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1 solution
If r is positive integer, i.e. 1,2,3,4..... Hence n = 4r-2 will be 2, 6, 10, 14...... Eg. If n is 2, 2 terms of the sum is 1+1=2 If n is 6, 6 terms of the sum is 1+1-1-1+1+1=2 Hence, the answer is 2.