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CarolineJean

Can someone explain to me, STEP BY STEP how to do this problem please, its Algebra 2-Complex numbers. -6(x+5)^2=120

  • one year ago
  • one year ago

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  1. hartnn
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    first divide both sides by -6 what u get ?

    • one year ago
  2. hartnn
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    and u should know that \(\huge \sqrt{-1}=i\)

    • one year ago
  3. matricked
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    6(x+5)^2+120 = (x+5)^2 - 20i^2 =0 ( and then factorise ) as i^2 =-1

    • one year ago
  4. 1on1
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    hartn good explanation and asking for participation . well done !!

    • one year ago
  5. Dido525
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    |dw:1352352097064:dw|

    • one year ago
  6. richyw
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    \[-6(x+5)^2=120\]\[(x+5)^2=-\frac{120}{6}\]\[x+5=\sqrt{-\frac{120}{6}}\]\[x+5=\sqrt{-20}\]\[x=\sqrt{-20}-5\]\[x=\sqrt{20}i-5\]\[x=\sqrt{4\cdot 5}i-5\]x=2\sqrt{5}i-5

    • one year ago
  7. Dido525
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    Now take the square root of the RHS .

    • one year ago
  8. richyw
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    \[x=2\sqrt{5}i-5\]

    • one year ago
  9. Dido525
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    Don't just post the answer...

    • one year ago
  10. hartnn
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    i don't think @CarolineJean wants any of your solutions, she wants to understand and none of you are helping by giving steps out...

    • one year ago
  11. CarolineJean
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    @hartnn yeah, thanks :)

    • one year ago
  12. richyw
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    oops just forgot the \(\pm\)

    • one year ago
  13. Dido525
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    Now take the square root. What do you get?

    • one year ago
  14. Dido525
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    I don't think you HAVE to simplify...

    • one year ago
  15. richyw
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    I dunno it's how I learn. sorry. I will leave.

    • one year ago
  16. CarolineJean
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    wow thanks everyone that helped alot :O i have a test tomorrow & didn't know how to do this type of problem but i understand now, thanks ^.^

    • one year ago
  17. 1on1
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    you go hartn !

    • one year ago
  18. Dido525
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    Ohh you understand? :) Good :) .

    • one year ago
  19. CarolineJean
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    omg the whole time i was trying to figure out how to do it i was trying to figure out how everyone was getting 20... i feel dumb now.... x)

    • one year ago
  20. Dido525
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    Haha :) .

    • one year ago
  21. richyw
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    if you are following my (huge list) of steps. just don't forget to take bot the positive and negative root. So you should get \(x=-2i\sqrt{5}-5\) and \(x=2i\sqrt{5}-5\)

    • one year ago
  22. hartnn
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    x=.... OR x=... either of them is a solution, not both

    • one year ago
  23. CarolineJean
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    yay ! i got that ! @richyw

    • one year ago
  24. CarolineJean
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    thank you to the only 2 ppl that really explained what to do lol @hartnn @richyw

    • one year ago
  25. Dido525
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    Not me? ;) . Jk Jk . Glad you understood :) .

    • one year ago
  26. CarolineJean
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    sorry didn't see yours ! :O @Dido525

    • one year ago
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