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1+2+3+........+90=
Calculati


Răspuns :

SE APLICA REGULA LUI Gauss    1+2+3+,,,,,n=n·(n+1)/2          
1+2+,,,,,,,,,,90=90·91/2=45·91=4095
[tex]\displaystyle 1+2+3+...+90= \frac{90(90+1)}{2} = \frac{90 \times 91}{2} = \frac{8190}{2} =4095[/tex]