# algebra

posted by
**Marissa**
.

I'm pretty sure these are right but I just want to check.

1)Find the 20th term of the arithmetic sequence in which a1=3 and d=7

a.143

b.136

c.140

d.133

answer=b

2)Write an equation for the nth term of the arithmetic sequence -3,3,9,15...

a.an=n+6

b.an=6n+9

c.an=6n-9

d.an=n-3

answer=b

3)Find the two arithmetic means between 4 and 22

a.10,16

b.8,16

c.8,12

d.13,13

answer=a

4)Simplify:Find Snfor the arithmetic series in which a1=3,d=1/2,and an=15

a.225

b.9

c.45

d.210

answer=b

5)I don't know how to type this but its like this in my book.

Find; 8 is on top of the sigma notation and k=3 is at the bottom(40-3k) is on the right side

a.45

b.282

c.-90

d.141

answer=d