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
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hartnn
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first divide both sides by -6
what u get ?
hartnn
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and u should know that \(\huge \sqrt{-1}=i\)
matricked
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6(x+5)^2+120 =
(x+5)^2 - 20i^2 =0 ( and then factorise ) as i^2 =-1
1on1
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hartn good explanation and asking for participation . well done !!
Dido525
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|dw:1352352097064:dw|
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
Dido525
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Now take the square root of the RHS .
richyw
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\[x=2\sqrt{5}i-5\]
Dido525
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Don't just post the answer...
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...
CarolineJean
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@hartnn yeah, thanks :)
richyw
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oops just forgot the \(\pm\)
Dido525
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Now take the square root. What do you get?
Dido525
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I don't think you HAVE to simplify...
richyw
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I dunno it's how I learn. sorry. I will leave.
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 ^.^
1on1
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you go hartn !
Dido525
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Ohh you understand? :) Good :) .
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)
Dido525
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Haha :) .
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 \(x=2i\sqrt{5}-5\)
hartnn
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x=.... OR x=...
either of them is a solution, not both
CarolineJean
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yay ! i got that ! @richyw
CarolineJean
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thank you to the only 2 ppl that really explained what to do lol
@hartnn @richyw
Dido525
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Not me? ;) . Jk Jk . Glad you understood :) .
CarolineJean
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sorry didn't see yours ! :O @Dido525