Răspuns:
Explicație pas cu pas:
n = numar par; n + 1 = numar impar; n + 2 = numar par
(-1)^numar par = 1
(-1)^numar impar = -1
1/2 - 1/3 + 1/6 = 3/6 - 2/6 + 1/6 = 2/6 = 1/3
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n = numar impar; n + 1 = numar par; n + 2 = numar impar
-1/2 + 1/3 - 1/6 = -3/6 + 2/6 - 1/6 = -2/6 = -1/3
