Răspuns:29
prima suma telescopica=1-1/2+1/2-1/3+1/3-1/4+1/4-.......+1/44-1/45
=1-1/45
a doua suma telescopica
=1/45-1/46+1/46-1/47+1/47-1/48+1/48-.......+1/89-1/90
=1/45-1/90
dif celor 2 sume=1-1/45-(1/45-1/90)
1-1/45-1/90
44/45-1/90
88/90-1/90
87/90
radical din 29*30*(87/90)
din 29*30*(29/30)
radical din 29*29=>29
