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anonymous

  • one year ago

What is the 9th term of the geometric sequence 4, -20, 100, …? -312,500 -12,500 62,500 1,562,500

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  1. alekos
    • one year ago
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    \[a _{n}=a _{1}r ^{n-1}\]

  2. alekos
    • one year ago
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    where n=9, a1=4 and I'll let you work out the common ratio r

  3. anonymous
    • one year ago
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    How do you find the common ratio?

  4. alekos
    • one year ago
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    just divide the second term by the first term or 3rd by the 2nd

  5. alekos
    • one year ago
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    thats the common ratio between terms

  6. anonymous
    • one year ago
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    Its it 5?

  7. anonymous
    • one year ago
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    Is the common ratio a 5?

  8. alekos
    • one year ago
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    No it's -20/4 = -5

  9. alekos
    • one year ago
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    now just plug the values into the equation

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