Respuesta :

semsee45

Answer:

388.79 (nearest hundredth)

Step-by-step explanation:

Given sequence:  324, 54, 9, ...

Therefore:

[tex]a_1=324[/tex]

[tex]r=\textsf{common ratio}=\dfrac{54}{324}=\dfrac16[/tex]

Sum of a finite geometric series:

[tex]S_n=\dfrac{a_1-a_1r^n}{1-r}[/tex]

Sum of the first 6 terms → n= 6:

[tex]\begin{aligned}S_6 & =\dfrac{324-324(\frac16)^6}{1-\frac16}\\ & =\dfrac{324-\frac{1}{144}}{1-\frac16}\\ & =\dfrac{9331}{24}\\ & = 388.79\:\textsf{(nearest hundredth)}\end{aligned}[/tex]
  • a=324 [A1 to be used as a]
  • Common ratio:=r=9/54=1/6

So

[tex]\\ \rm\Rrightarrow S_n=\dfrac{a-ar^n}{1-r}[/tex]

[tex]\\ \rm\Rrightarrow S_6=\dfrac{324-324(1/6)^6}{1-1/6}[/tex]

[tex]\\ \rm\Rrightarrow S_6=\dfrac{324-\dfrac{1}{12^2}}{\dfrac{5}{6}}[/tex]

[tex]\\ \rm\Rrightarrow S_6=\dfrac{9331}{24}=388.79[/tex]