Question

calculati sumele va rog hellp

Answer 1

Se rezolva cu formula:
   (primul + ultimul) x cate sunt
--------------------------------------------
                          2

a. (1+102)x102               103x102               10506 
-----------------------   =   -------------------  =  ----------------   =  5253
             2                               2                        2

Answer 2

S₁=1+2+....+102=102·(102+1)/2=102·103/2=10506/2=5235
S₂=35+36+...+82=1+2+...+82-(1+2+...+34)=82(82+1)/2-(34(34+1))/2=82·83/2-34·35/2=41·83-17·35=3403-595=2808
S₃=1+2+...+75=75·(75+1)/2=75·76/2=75·38=2850
S₄=52+53+...+122=1+2+...+122-(1+2+...+51)=122(122+1)/2-51(51+1)/2=122·123/2-51·52/2=61·123-51·26=7503-1326=6177
Asa cum ai observat am utilizat Sumele Gauss.
Spor la lucru!