Grace A.

asked • 11/17/12

find the 15th term of the sequence: a_(n)=(-1)^n (n+1)

I believe this is a geometric sequence.

1 Expert Answer

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Roman C. answered • 11/17/12

Masters of Education Graduate with Mathematics Expertise

Do you mean an = (-1)n * (n+1) ?

In that case, just plug in n=15.

a15 = (-1)15 * (15+1) = -1 * 16 = -16

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Grace A.

Yes, thanks so much!!
What about this one?
find the 3rd term in the sequence: an =(-1)n+15n+1

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11/17/12

Roman C.

tutor

a3 = (-1)3+153+1 = (-1)454 = 1*625 = 625

Now see if you can compute some other problems with calculating terms in sequences. These two examples should give you the enough of an idea. I assume these are from a textbook. Good Luck!

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11/17/12

Grace A.

Thanks! But would it not be -625?

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11/17/12

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