Question

Calcule a soma dos termos de cada PG

a)( 729,243,81,27,9,3,1)

b)(81/32,27/16,...,1/2)

Answer 1

• RAZÕES  $q1=\frac{243}{729} =\frac{1}{3} \\q2=\frac{\frac{27}{16} }{\frac{81}{32} }=\frac{864}{1296}=\frac{2}{3}$

• VALOR DE N PARA LETRA B  $an=a1*q^{n-1} \\\frac{1}{2} = \frac{81}{32}\frac{2}{3} ^{n-1}\\ n=5$

• LETRA A   $S=\frac{729(\frac{1}{3} ^{7}-1) }{\frac{1}{3} -1}=1093$

• LETRA B    $S=\frac{\frac{81}{32} (\frac{2}{3} ^{5}-1) }{\frac{2}{3} -1}=6,6$