Question

Urgent !! Explicati-mi si mie exercitiile astea nu le inteleg !! :((
1. Fie n1 = 1 + 3 + 5 + 7 +.....+99 si n2 = 2 + 4 + 6 + 8 +....+100. Precizati valoarea de adevar a propozitiilor :
a) 2 | n1
b) 10 | n1 + n2
c) 5 | n2- n1

Answer 1

Pai ai formula de calcul:
n1=(99+1)*50:2=2500, iar n2=2(1+2+3+4+...+50)=2*[50(50+1):2]=2550.
a) 2500-par => 2 | n1.
b) n1+n2=5050; 10|5050 => 10| n1+n2
c) n2-n1=50; 5|50 deci 5|n2-n1.