Question

1+3+5+...+11=
Nu inteleg cum se face suma lui Gaus cu numere impare..

Answer 1

S = 1 + 3 + .. + 11

S = (2*0 + 1) + (2*1 + 1) + .. + (2*5 + 1)

S = 2(1 + 2 + .. + 5) + 1*6

S = 2*5*6 : 2 + 6

S = 30 + 6

S = 36

Sau ai formula

1 + 3 + .. + 2n - 1 = n²

2n - 1 = 11

2n = 12

n = 6

S = 1 + 3 + .. + 11 = 6² = 36