Question

Calcule a soma 205 50° primeiros termos da pa (4,7,10,..) ?​

Answer 1

resolução!

r = a2 - a1

r = 7 - 4

r = 3

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an = a1 + ( n - 1 ) r

an = 4 + ( 50 - 1 ) 3

an = 4 + 49 * 3

an = 4 + 147

an = 151

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Sn = ( a1 + an ) n / 2

Sn = ( 4 + 151 ) 50 / 2

Sn = 155 * 50 / 2

Sn = 7750 / 2

Sn = 3875