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dellzasaur

  • 2 years ago

Can someone please check my work?? Wanna make sure I'm doing this right! Simply each number by using the imaginary number i. thanks!

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  1. dellzasaur
    • 2 years ago
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    \[\sqrt{-7}\] = 7i or \[i \sqrt{7}\]

  2. dellzasaur
    • 2 years ago
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    \[\sqrt{-81}\] = 3i

  3. dellzasaur
    • 2 years ago
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    \[\sqrt{-16}\] = \[2i \sqrt{4}\]

  4. dellzasaur
    • 2 years ago
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    \[3\sqrt{-9}\] = \[3i\]

  5. Dido525
    • 2 years ago
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    The last one is wrong.

  6. dellzasaur
    • 2 years ago
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    @dido525 Oh wow!! Thank you. I can't believe I'm doing these somewhat right lol. Would it be \[3i \sqrt{3}\] ?? And there was also a problem that was \[\sqrt{-72}\] I got: \[2i \sqrt{3}\]

  7. Dido525
    • 2 years ago
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    The last one should be 9i.

  8. Dido525
    • 2 years ago
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    Well think about it WITHOUT the negative.

  9. Dido525
    • 2 years ago
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    |dw:1352593737003:dw|

  10. Dido525
    • 2 years ago
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    |dw:1352593754329:dw|

  11. Dido525
    • 2 years ago
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    Now what would you do?

  12. dellzasaur
    • 2 years ago
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    is that a 4 and 18? I would think to factor them to 2 x 2 and 9 x 2 maybe

  13. dellzasaur
    • 2 years ago
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    but inside of the radicals

  14. dellzasaur
    • 2 years ago
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    |dw:1352593862710:dw|

  15. dellzasaur
    • 2 years ago
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    @Dido525

  16. Dido525
    • 2 years ago
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    No No.

  17. Dido525
    • 2 years ago
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    |dw:1352594047004:dw|

  18. dellzasaur
    • 2 years ago
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    @Dido525 Oh ok! That made since. I was using 8, 9, and i to make -72

  19. Dido525
    • 2 years ago
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    Okay :) .

  20. dellzasaur
    • 2 years ago
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    @Dido525 Thank you so much for all your help :) Makes me feel more confident about simplying them!

  21. dellzasaur
    • 2 years ago
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    *simplifying whoops

  22. Zarkon
    • 2 years ago
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    \[\sqrt{-72}=\sqrt{(-1)\cdot2\cdot 36}\] \[=6i\sqrt{2}\]

  23. Dido525
    • 2 years ago
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    Okay that works too.

  24. chaguanas
    • 2 years ago
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    Getting the i right, but need to look at \[\sqrt{81} and \sqrt{16}\]

  25. dellzasaur
    • 2 years ago
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    @chaguanas Would I do \[3i \sqrt{3}\] for -81? and 4i or \[4i \sqrt{4}\] for -16?

  26. Zarkon
    • 2 years ago
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    do you know what \(\sqrt{81}\)is?

  27. dellzasaur
    • 2 years ago
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    @Zarkon 9

  28. Zarkon
    • 2 years ago
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    well...\[\sqrt{-81}=\sqrt{(-1)81}=i9=9i\]

  29. dellzasaur
    • 2 years ago
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    @Zarkon Ohh so that's how you do it. You wouldn't factor the 9 out to a 3?

  30. Zarkon
    • 2 years ago
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    no

  31. Zarkon
    • 2 years ago
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    for any \(a>0\) \[\sqrt{-a^2}=a\cdot i\] so \[\sqrt{-81}=\sqrt{-9^2}=9i\]

  32. Zarkon
    • 2 years ago
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    \[\sqrt{-16}=\sqrt{-4^2}=4i\]

  33. dellzasaur
    • 2 years ago
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    @Zarkon Oh alright! I'm not sure if my teacher taught me about the a>0 thing but that makes sense. Thank you very much :) Explained a lot.

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