Sequences and series

Find the SUM of the first four terms of the geometric sequence that begins with 1 with a common ratio of 3.

• 25

• 37

• 40

• 80

Evaluate the geometric series described below.
 $a_1=-1,\ r\ =\ 4,\ n\ =\ 8$  

• -585

• 585

• -21,845

• 21,845

• -63

• 63

• -31

• 31

• 80

• 120

• 160

• 242

Find the indicated sum for the geometric series.
S₆ for (-4/5) + 8 + (-80) + 800 + ....

• _S6 = 21,845
• _S6 = 72,000
• _S6 = 72,727.2
• _S6 = -128,840.8

Find the sum of the first 9 terms:  -2 + -6 + -18 + ...  

• -59,048
• -39,366
• -19,682
• -4,374

Which formula would determine the SUM of the first 8 terms of the following sequence?

75, 70.5, 66.27,...

• $S_n=\frac{75-75\left(.94\right)^8}{1-.94}$

• $S_n=\frac{75-75\left(1.06\right)^8}{1-1.06}$

• $a_n=75\left(.94\right)^{8-1}$

• $a_n=75\left(1.06\right)^{8-1}$

What is the SUM of the first 10 terms for the following geometric series:

2-6+18-54+...

• 59048

• -29524

• 524288

• 3069

In a geometric sequence a₁ = 12 and r = √2.  What is the approximate sum of the first 20 terms of the sequence?

• 339.4
• 8688.9
• 29624.9
• 29636.9

Which of the following represents the value of  $\sum_{i=0}^8256\left(\frac{3}{2}\right)^i$  ?

 Think carefully about how many terms this series has in it.

• 19,171

• 12,610

• 22,341

• 8,956