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Calculati: 2017-1-2- 3....-50

Răspuns :

2017-1-2- 3....-50 =
2017-(1+2+...+50)=
2017-50*51:2=
2017-25*51=
2017-1275=742
syma lui gauss:1+2+3+...+n=n*(n+1):2
2017-1-2-3-...-50 = 2017 - (1 + 2 + 3 + ... + 50) = 2017 - (50 * 51) : 2 = 2017 - 25 * 51 = 2017 - 1275 = 742