Răspunsuri

Cel mai inteligent răspuns!
2014-09-27T15:14:42+03:00

1/4 (1/1-1/5)+ 1/4(1/5 - 1/9) + ................................+ 1/4[1/(4n-3) - 1/(4n+1)] = 1/4[1/1 - 1/5+1/5 -1/9 +1/9 -................................1/(4n-3) - 1/(4n+3)]   =     1/4[ 1- 1/(4n+1)] = 1/4×[ (4n) /(4n+1)] = n/(4n+1)

1 5 1