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calculati suma
5=2+4+6+8+10+.....+500


Răspuns :

2+4+6+8+10+.....+500=
2 (1+2+..+250 )=2 (250x251:2)=250x251=62750
2+4+6+8+10+.....+500=2 x(1+2+..+250 )=2 x(250x251:2)=62750
1+2+3+..+n=nx(n+a):2-sirul gauss

deci 5 nu este egal cu 62750