Question

dati factor comun si calculati urmatoarele sume:
S=5,10,15,...300
S=7,14,21,28,35...700
S=11,22,33,...264

Answer 1

Răspuns

Explicație pas cu pas:

S = 5 + 10 + 15 + ....... + 300

S = 5 x ( 1 + 2 + 3 + ..... + 60 )

S = 5 x 60 x ( 1 + 60 ) : 2

S = 300 x 61 : 2

S = 9 150

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S = 7 + 14 + 21 + 28 + ...... + 700

S = 7 x ( 1 + 2 + 3 +......... + 100 )

S = 7 x 100 x ( 1 + 100 ) : 2

S = 700 x 101 : 2

S = 35 350

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S = 11 + 22 + 33 + ....... + 264

S = 11 x ( 1 + 2 + 3 + ..... + 24 )

S = 11 x 24 x ( 1 + 24 ) : 2

S = 11 x 12 x 25

S = 3 300

Answer 2

s=5 (1+2+3+...+60)
s=5((60+1):2)
s=5*61÷2
s=9150

S=7(1+2+3+...100)
s=7(100+1)÷2
s=7 *101÷2
s= 35350

S=11(1+2+3+...+24)
s=11(24+1)
s=11*25
s=3300