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1+2+3+...+100-51-52...-102

Răspuns :

[tex]1+2+3+...+100 -51-52-...-102= \\ \\ =1+2+3+...+100-(51+52+...+100)-101-102= \\ \\ =1+2+3+...+50-101-102= \\ \\ = \frac{50 \cdot 51}{2}-203= \\ \\ =25 \cdot 51-203= \\ \\ = 1275-203= \\ \\ =1072.[/tex]