12 + 14 + 16 = 42 poltronas
620 : 42 = aproximadamente 15 fileiras
An=12(n-1) *2 Sn=(a1+an) *n/2 An= 12+2n-2 620=(12+2n+10)*n/2
An=2n+10 620= 12n+2n^2+10n/2
620=6n+n^2+5n.
N^2+11n-620=0
X1=20.x2=-31 logo 20 poltronas e a resposta certa.
Copyright © 2024 ELIBRARY.TIPS - All rights reserved.
Lista de comentários
12 + 14 + 16 = 42 poltronas
620 : 42 = aproximadamente 15 fileiras
An=12(n-1) *2 Sn=(a1+an) *n/2 An= 12+2n-2 620=(12+2n+10)*n/2
An=2n+10 620= 12n+2n^2+10n/2
620=6n+n^2+5n.
N^2+11n-620=0
X1=20.x2=-31 logo 20 poltronas e a resposta certa.