Question

Find the sum of a finite geometric sequence from n = 1 to n = 5, using the expression −3(4)n − 1.
-1,023

1,223

1,023

−4,374

Answer 1

@gswag98

Answer 2

@jdoe0001

Answer 3

hey what class is this

Answer 4

\(\bf -3(4)^{n-1}\) right?

Answer 5

Yeah c:

Answer 6

Its Algebra 2 xD

Answer 7

All i know is, i will never have to use this in life.

Answer 8

"SNAP" can't help ya then

Answer 9

\(\bf \large {
S_{\color{brown}{ n}}=\Sigma_{i=1}^n\ a_1\cdot r^{i-1}=a_1\left(\cfrac{1-r^{\color{brown}{ n}}}{1-r}\right)
\\ \quad \\
thus \implies -3(4)^{n-1} \iff a_1\cdot r^{i-1}\to
\begin{cases}
a_1=-3\\
\bf r=4
\end{cases}
\\ \quad \\
S_{\color{brown}{ 5}}=\Sigma_{i=1}^{\color{brown}{ 5}}\ a_1\cdot r^{i-1}=-3\left(\cfrac{1-4^{\color{brown}{ 5}}}{1-4}\right)
}\)

Answer 10

WHAT.

Answer 11

heheh

Answer 12

\(\bf \large S_{\color{brown}{ n}}\) <-- finite sequence sum

Answer 13

Okay so. 341?

Answer 14

341*3=1023

Answer 15

hard 2 understand all that on @jdoe0001 's pic

Answer 16

OH I GOT IT ;D

Answer 17

well... is a notationi for a geometric sequence =)

Answer 18

Help with one more? ;3

Answer 19

yeap is 1023