1+2+3+4........+10
7+8+9+.........+82+83
1+3+5........27+29
5+10+15......+80
21+28+35+........147
2+5+16+......142
suma GAUSS va rog mult!!!❤
Răspunsuri la întrebare
1 + 2 + 3 + 4 + ........ + 10 = 10 × ( 1 + 10 ) / 2 = 5 × 11 = 55
S = 7 + 8 + 9 + ......... + 82 + 83
→ stabilesc cati termeni are suma, cu ratia 1
83 - 7 + 1 = 76 + 1 = 77 termeni
S = 77 × ( 7 + 83 ) / 2
S = 77 × 90 / 2
S = 77 × 45
S = 3 465
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1 + 3 + 5 + ........ + 27 + 29 = 225
= [ ( 29 - 1 ) : 2 + 1 ] × ( 1 + 29 ) / 2 = 15 × 30 / 2 = 15 × 15 = 225
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S = 5 + 10 + 15 + ...... + 80
S = [ ( 80 - 5 ) : 5 + 1 ] termeni × ( 5 + 80 ) / 2
S = 16 × 85 / 2
S = 8 × 85
S = 680
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21 + 28 + 35 + ........ + 147 = 1 596
→ stabilesc cati termeni are suma cu ratia 7 ( 28 - 21 = 7; 35 - 28 = 7 )
( 147 - 21 ) : 7 + 1 = 126 : 7 + 1 = 18 + 1 = 19 termeni are suma
→ aplic formula sumei lui Gauss
= 19 × ( 21 + 147 ) / 2 =
= 19 × 168 / 2 =
= 19 × 84=
= 1 596