Răspuns:
Explicație pas cu pas:
1/1x2 = 1/1 - 1/2
1/2x3 = 1/2 - 1/3
1/3x4 = 1/3 - 1/4
............
1/49x50 = 1/49 - 1/50
__________________
S = 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + ....+ 1/49 - 1/50
= 1 - 1/50 = 50/50 - 1/50 = 49/50
