Question

Few Algebra 2 problems to finish up my course!

What is the 41st term of the arithmetic sequence where a1 = 17 and a15 = -39 ?

-147
-143
-139
-135

What is the sum of a 30-term arithmetic sequence where the first term is 72 and the last term is -102?

-480
-450
-420
-390

What is the 7th term of the geometric sequence where a1 = -2 and a5 = -512?

-2,048
-8,192
2,048
8,192
What is the 6th term of the geometric sequence where a1 = -4,096 and a4 = 64?

-1
4
1
-4

What is the sum of the geometric sequence -3, 21, -147, ... if there are 6 terms?

11,772
-352,947
44,118
-179,132
What is the sum of the geometric sequence 2, 8, 32, ... if there are 8 terms?

21,845
43,690
65,535
87,380

Answer 1

ok...

Answer 2

1st Problem: Look at this:

http://openstudy.com/study#/updates/50f77e29e4b007c4a2eb5c88

Answer 3

Thank heavens

Answer 4

Okay so -143

Answer 5

These are new

Answer 6

The review to my final

Answer 7

2) Sum of first n terms of arithmetic sequence is n(a1 + An) / 2 where n is the number of terms and a1= first term and an = last term.

Sum = 30 * ( 72 - 102 ) / 2.

So, Sum = ?
@tinaballerina

Answer 8

-450

Answer 9

Yes. I did have -480 but made an error.

Answer 10

For #3, I looked at a powers of 2 chart. See attached.

Answer 11

We're multiplying each term by 4 or -4.

Answer 12

Which do you think? Once we know, we can jump to the 7th term.

Answer 13

@tinaballerina