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Cum se calculeaza suma :
S=5+7+9+11+...........+203


Răspuns :

(203-5):2+1=

198:2+1

99+1

100

S=100x(5+203):2

S=100x208:2

S=20800:2

S=10400

1 + 3 + .. + 2n - 1 = n²

2n - 1 = 203 => 2n = 204 => n = 102

S = (1 + 3) + 5 + .. + 203 - (1 + 3) = 102² - 4 = 10404 - 4 = 10400