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1/7+1/91+1/247+...+1/8827​

Răspuns :

Răspuns:

16/97

Explicație pas cu pas:

1/1*7+1/7*13+1/13*19+....1/91*97

1/1*7=(1/6)*(1/1-1/7)

1/7*13=(1/6)*(1/7-1/13)

1/13*19=(1/6)(1/13-1/19)

.........................

1/91*97=(1/6)*(1/91-1/97)

toat suma

(1/6) * (1-1/7+1/7-1/13+1/13-1/19+.....+1/91-1/97)=

(1/6)*(1-1/97)

(1/6)*96/97=16/97