Question

cum se calculeaza :
1+3+5+...+101?

Answer 1

2·0+1+2·1+1+2·2+1....+ 2 · 50 +1=
= 2( 1+2+...+50 )=
=2 · 50 ·51 ÷2=50·51= 2550

Answer 2

101=2×n-1
101-1=2×n
100=2×n
n=100:2
n=50
1+3+5+...+101=n la puterea a 2
1+3+. . . + 101=50 la puterea a 2
1+3+...+101=2500