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anonymous

  • one year ago

Write the sum using summation notation, assuming the suggested pattern continues. -9 - 3 + 3 + 9 + ... + 81 Could someone please help?? I will medal, but I just don't understand these problems.

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  1. Hero
    • one year ago
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    Hint: Write the numbers as exponents.

  2. anonymous
    • one year ago
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    So... -3^2 - 3^1 + 3^1 + 3^2 ...

  3. anonymous
    • one year ago
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    @Hero

  4. Hero
    • one year ago
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    Yes

  5. Hero
    • one year ago
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    Write 81 as an exponent

  6. anonymous
    • one year ago
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    9^2 or 3^4 ? @Hero

  7. Hero
    • one year ago
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    Think about it.

  8. anonymous
    • one year ago
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    Yes, it is 3^4, so in total: -3^2 - 3^1 + 3^1 + 3^2 ... 3^4

  9. anonymous
    • one year ago
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    @Hero

  10. Hero
    • one year ago
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    Good. What number exists between 3^2 and 3^4?

  11. anonymous
    • one year ago
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    3^3

  12. Hero
    • one year ago
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    Exactly. So now you can write using summation notation since you have the complete pattern.

  13. anonymous
    • one year ago
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    I'm confused on how to write it into summation notation.

  14. Hero
    • one year ago
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    Do you know what summation notation looks like?

  15. anonymous
    • one year ago
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    Yes, I do.

  16. Hero
    • one year ago
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    Well, then you should try your best to write the pattern in summation notation. Don't be afraid to make a mistake.

  17. anonymous
    • one year ago
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    Ok I'll give it a try. Thanks!

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