Răspuns :

Răspuns:

Explicație pas cu pas:

1/2*3 = 1/2 - 1/3

1/3*4 = 1/3 - 1/4

1/4*5 = 1/4 - 1/5

1/29*30 = 1/29 - 1/30

1/2*3 + 1/3*4 + 1/4*5 + ...+ 1/29*30 = 1/2 - 1/3 + 1/3 - 1/4 + 1/4 - 1/5 + ...+ 1/29 - 1/30 = 1/2 - 1/30 = 15/30 - 1 /30 = 14/30 = 7/15 = 0,4(6) ∈ [0,(3); 0,5]

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