Question

calculati sumele:

a) S=1/1*3 + 1/3*5+.....+1/57*59

b) S=1/1*4+1/4*7+1/7*10+....+1/97*100

Answer 1

(1/2)* (1/1-1/3+1/3-1/5+...+1/55-1/57+1/57-1/59)=(1/2)*(1-1/59)=(1/2) *58/59=29/59

(1/3)* (1-1/4+1/4-1/7+1/7-1/10+1/94-1/97+1/97-1/100)=(1/3)*(1-1/100)=

(1/3) *(99/100)=33/100=0,33