Question

qual a soma dos multiplos de 4 compreendidos entre 10 e 205

Answer 1

an = a1 + ( n - 1 ) r

204 = 12 + ( n - 1 ) 4

204 = 12 + 4n - 4

204 = 8 + 4n

204 - 8 = 4n

196 = 4n

n = 196/4

n = 49

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Sn = ( a1 + an ) n / 2

Sn = ( 12 + 204 ) 49 / 2

Sn = 216 * 49 / 2

Sn = 10584 / 2

Sn = 5292