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Mathematics 8 Online
OpenStudy (beccab003):

radical

OpenStudy (beccab003):

@DanJS

OpenStudy (danjs):

k

OpenStudy (beccab003):

\[(-3\sqrt{-5})(-3\sqrt{-5})\]

OpenStudy (beccab003):

or \[(-3\sqrt{5})^2\]

OpenStudy (danjs):

yeah, just think of it as multiplication of all 4 of the terms

OpenStudy (danjs):

-3*-3*root5*root5

OpenStudy (danjs):

\[(-3*-3)*\sqrt{5*5} = 9*\sqrt{25} = 9*5 = 45\]

OpenStudy (beccab003):

\[9\sqrt{25}\]

OpenStudy (danjs):

yep

OpenStudy (beccab003):

wait..but you got 45??

OpenStudy (danjs):

square root of 25 is 5

OpenStudy (danjs):

o wait you have -5 in there,

OpenStudy (danjs):

there will be some of those i's involved because of the negative under the radical

OpenStudy (danjs):

\[(-3*-3)\sqrt{-1*5}*\sqrt{-1*5}\]

OpenStudy (danjs):

\[9*\sqrt{-1}\sqrt{-1}\sqrt{25}\]

OpenStudy (danjs):

remember, i = root(-1)

OpenStudy (danjs):

\[9 * i*i * 5\]

OpenStudy (danjs):

45i^2 and i^2 = -1 45*-1 -45

OpenStudy (beccab003):

Okay, I see it now. So, there is not an i in the answer correct? just -45?

OpenStudy (danjs):

right, only an i if the i has an odd power i^1=i i^2=-1 i^3=-i i^4=1

OpenStudy (beccab003):

okay

OpenStudy (beccab003):

switching gears for a sec....what is a conjugate?

OpenStudy (danjs):

conjugate pair i think , remember those denominators that had \[a +\sqrt{b}\]

OpenStudy (danjs):

then you multiply that by the conjugate \[a - \sqrt{b}\]

OpenStudy (beccab003):

okay. I thought it was where you switch the signs but I wasn't sure.

OpenStudy (danjs):

yeah, it is any binomial ( a thing that has 2 terms), with the sign switched

OpenStudy (danjs):

binomial a + root(b) conjugate a - root(b)

OpenStudy (beccab003):

thanks.

OpenStudy (beccab003):

I only have a few more questions that I am stumped on if you could help....I normally wouldn't ask you to help with a lot of questions but I want to be able to be prepared for my test. Afterwords...I won't be bothering you anymore. :)

OpenStudy (danjs):

no prob, start a new thread so i can get more medals. lol

OpenStudy (beccab003):

haha :)

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