# Thread: Confused with this problem?

1. ## Confused with this problem?

Q: What is the a8 term of the sequence [an] if an equals
a.) 2n - 1 ?
b.) 7?
c.) 1 + (-1)n ?
d.) – (-2)n ?
I am confused on what to do here?

2. I cant' Edit, so I repost the problem:

Q: What is the a8 term of the sequence [an] if [an] equals
a.) 2^(n - 1) ?
b.) 7?
c.) 1 + (-1)^(n) ?
d.) – (-2)^(n) ?
I am confused on what to do here?

3. Originally Posted by Grillakis

Q: What is the a8 term of the sequence [an] if [an] equals
a.) 2^(n - 1)
b.) 7
c.) 1 + (-1)^(n)
d.) – (-2)^(n)

I am confused on what to do here?
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If $\displaystyle a_n = 2^{n-1}$

Then Put $\displaystyle n=8$ to get $\displaystyle n_8 = 2^{7}$

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If $\displaystyle a_n= 7$

Then the complete sequence is $\displaystyle 7 ,7, 7, 7 ,7 ,7...$

Hence $\displaystyle a_8 = 7$

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If $\displaystyle a_n= 1+(-1)^n$

Since $\displaystyle (-1)^{even~number}=1$

Thus $\displaystyle a_8=1 + {-1}^8 = 2$

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If $\displaystyle a_n = -(-2)^n$

Then $\displaystyle a_8 = - (-2)^{8} = -(-1)^8\times (2)^8$

Thus $\displaystyle a_8 = -(2)^8$

4. ok thanks....so all you do than really is whatever n is, you put that number in the equation. I see. Thanks.