Question

Determine a soma dos termos de cada PA.
(-8,-5,-2,...,22)

Answer 1

1_passo calcule o termo geral an=a1+(n-1).r 22=-8+(n-1).3 22=-8+3n-3 22=-11+3n 22+11= 3n 33=3n 3n=33 n= 33/3 n= 11 2_ passo calcule a soma do número de termos Sn=(a1+an).N/2 Sn=(-8+22).11/2 Sn=14.11/2 Sn=154/2 Sn= 77 Obrigado .