# algebra(check)

posted by
**Marissa**
.

1)Find the sixth term of the geometric sequence for which a1=5 and r=3

a.1215

b.3645

c.9375

d.23

answer=a

2)Write an equation for the nth term of the geometric sequence -12,4,-4/3,...

a.an=-12(1/3)n-1

b.an=12(-1/3)n-1

c.an=-12(-1/3)-n+1

d.an=-12(-1/3)n-1

answer=d

3)Find four geometric means between 5 and 1215

a.+-15,45,+-135,405

b.15,45,135,405

c.247,489,731,973

d.+-247,489,+-731,973

answer=d

4)Find the sum of the geometric series 128-64+32-_____to 8 terms

a.85

b.255

c.86

d.85/2

answer=a

5)Find 6 on top of sigma notation n=1 on the bottom 5(-4)n-1 on the right side.

a.6825

b.-4095

c.-1023

d.-5120

answer=b