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Cosmi0986
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CALCULAȚI A. S=2+4+6+.......+100=
B. (3+6+9.......+50):3

Răspuns :

Cocirmariadenis

a)   S = 2 + 4 + 6 + ..... + 100

S = 2 × ( 1 + 2 + 3 + ...... + 50 )

S = 2 × 50 × ( 1 + 50 ) : 2

S = 50 × 51

S = 2 550

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b)   S = ( 3 + 6 + 9 + ............51 ) : 3

S = 3 × ( 1 + 2 + 3 + ..... + 17 ) : 3

S = 17 × ( 1 + 17 ) : 2

S = 17 × 18 : 2

S = 17 × 9

S = 153

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