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Mathematics 15 Online
OpenStudy (vera_ewing):

Check my answer please

OpenStudy (anonymous):

Don't think so. The common ratio is -2.

OpenStudy (welshfella):

none of them are correct common ratio = -10 according to the question.

OpenStudy (anonymous):

Common ratio is any term divided by the term immediately preceding it.\[\frac{ -10 }{ 5 } = -2\]

OpenStudy (welshfella):

oh sorry I misread the question The second term is -10.!!!

OpenStudy (welshfella):

as ospreytriple has said the common ratio r can be found by second term / first term = -10 / 5

OpenStudy (anonymous):

In general,\[a_n = a_1\left( r \right)^{n-1}\]For the first term (n=1) you would get\[a_1=a_1\left( r \right)^{1-1} = a_1\]In your question, \(a_1 = 5\) and \(r = -2\)

OpenStudy (welshfella):

hint: first term is when n = 1

OpenStudy (anonymous):

Well, if you think the answer is B, try n=0 and see what you get.

OpenStudy (anonymous):

Correct.

OpenStudy (welshfella):

its A

OpenStudy (vera_ewing):

Thank you

OpenStudy (anonymous):

You're welcome

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