Question

RAPID aflati rezulatul sumei :

a) 1+2+3+...+78

b) 3+6+9+12+...+159​

Answer 1

Răspuns:

a) (78×79/2 = 3081

b) 3 × (53×54)/2 = 3 × 1431 = 4293

Answer 2

Răspuns:

suma lui Gauss

a) 1+2+3+...+78=78·(78+1)/2=78·79:2=3081

b) 3+6+9+12+...+159​=

dam factor comun 3

3(1+2+3+...+53)=3·53·54/2=4293