Question

Calculati:
1/1*2+1/2*3+1/3*4+...+1/29*30
2/1*3+2/3*5+2/5*7+...+2/59*61
3/2*5+3/5*8+3/8*11+...+3*77*80
1/1*2+1/5*9+1/9*13+...+1/81*85
Va rog frumos!!!!

Answer 1

Răspuns:

descompui in sume partiale

tii cont de formula generala

1/n(n+k)=(1/k)* (1/n-1/(n+k))

Explicație pas cu pas: