Question

Aflati cat da 2+4+6+8+....+1000
si 1+3+5+....+99
PLS!!!E URGENT!

Answer 1

2(1+2+3+4+...+500) = 2 * 500*501/2
= 500*501
=0.99

(1+2+3+4+5+...+99) - (2+4+...+98) = 99*100/2 - 2(1+2+...+49)
= 99*50 - 49*50
=4950 - 2450
= 2500

{
 am folosit formula pentru suma Gauss: 1+2+...+n= n(n+1)/2
}