Question

1+3+5+......+2017 va rogg dau coroana​

Answer 1

Explicație pas cu pas:

suma Gauss pentru numere impare:1 + 3 + 5 + 7 + … + ( 2n – 1 ) = n · n

2n - 1 =2017

2n = 2017+1

2n =2018

n = 1009

b= 1 + 3 + 5 +... + 2017 = n² = 1009²

Answer 2

(1+2+3+4+5+....+2016+2017)-(2+4+6+...+2016)

1+2+3+4+5+...+ 2016 +2017= 2017×2018:2=2.035.153

2+4+6+...+2016= 2×1+2×2+2×3+...+2×1008=

=2×(1+2+3+...+1008) =2×(1008×1009:2)

=1.017.072

2.035.153-1.017.072=1.036.081