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CarolineJean

  • 3 years ago

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

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  1. hartnn
    • 3 years ago
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    first divide both sides by -6 what u get ?

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

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

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

  5. Dido525
    • 3 years ago
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    |dw:1352352097064:dw|

  6. richyw
    • 3 years ago
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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

  7. Dido525
    • 3 years ago
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    Now take the square root of the RHS .

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

  9. Dido525
    • 3 years ago
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    Don't just post the answer...

  10. hartnn
    • 3 years ago
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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...

  11. CarolineJean
    • 3 years ago
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    @hartnn yeah, thanks :)

  12. richyw
    • 3 years ago
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    oops just forgot the \(\pm\)

  13. Dido525
    • 3 years ago
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    Now take the square root. What do you get?

  14. Dido525
    • 3 years ago
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    I don't think you HAVE to simplify...

  15. richyw
    • 3 years ago
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    I dunno it's how I learn. sorry. I will leave.

  16. CarolineJean
    • 3 years ago
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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 ^.^

  17. 1on1
    • 3 years ago
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    you go hartn !

  18. Dido525
    • 3 years ago
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    Ohh you understand? :) Good :) .

  19. CarolineJean
    • 3 years ago
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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)

  20. Dido525
    • 3 years ago
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    Haha :) .

  21. richyw
    • 3 years ago
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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 \(x=2i\sqrt{5}-5\)

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

  23. CarolineJean
    • 3 years ago
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    yay ! i got that ! @richyw

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

  25. Dido525
    • 3 years ago
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    Not me? ;) . Jk Jk . Glad you understood :) .

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

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