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Alexandru1979
a fost răspuns

CALC
4+8+12+...+364=
12+13+14+...+50=
8+9+10+....+70=
RAPIDDD

Răspuns :

Letitiasqn
S= 4 + 8 + ... +364 = 4( 1 + 2 + ... + 92) = 4 [92 ( 92 + 1 ) ] / 2= 2 ×92 × 93 = 17. 112

S = 12 + 13 + ... + 50 = 1 + 2 + ... + 11 + 12 + ... + 50 -( 1 + 2 + ... + 11) = 50( 50 + 1)/2 - 11( 11 + 1) / 2= 25 × 51 - 11 × 6 = 1. 209

S = 8 + 9 + 10 + ... + 70 = 1 + 2 + ... + 8 + 9 + ... +70 - ( 1 + 2 + ... + 7)= [ 70 ( 70 + 1) ] / 2 - 7 × ( 7 + 1 ) /2 = 35 × 71 - 7 × 4 = 2. 457

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