Question

Cum se calculează 1+3+5...............+99?

Answer 1

1+3+5+....+2n-1=n²
2n-1=99=>2n=100=>n=50

1+3+5+...+99 = 50² = 2500

Answer 2

=(99+1)+(97+3)+(95+5)+...+(49+50)=

In sirul 1,3,5,...,99 sunt (99+1):2=100:2=50 de numere

=100+100+100+...+100=
(In total, 100 se repeta de 50:2=25 de ori)
=100×25=
=2500