• Matéria: Matemática
  • Autor: Marinamalaquis
  • Perguntado 8 anos atrás

Quantos termos possui a p.a.-20,-12,...60

Respostas

respondido por: ALCACARENHO
1
a1 = -20
r = -12 - (-20) = 8
an = 60

an = a1 + (n-1)r
60 = -20 + (n-1) 8
60 = -20 + 8n - 8
60 = -28 + 8n
60+28 = 8n
88 = 8n
88/8 = n
11 = n

victorpsp666: A pergunta é "quantos termos"
ALCACARENHO: lol... sorry.. i dont understand portuguese.. i thought that was mean the fourth termo
ALCACARENHO: now i cant fix it bcs u reported it...
victorpsp666: http://prntscr.com/hman1v
victorpsp666: Marinamalaquis u reported*
respondido por: victorpsp666
0
r = -12 -(-20)
r = 8

an -a1 = (n -1) . r
60 +20 = (n -1) . 8
80/8 = n -1
10 + 1 = n
11 = n
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