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Mathematics 19 Online
OpenStudy (zuha):

Simplify the expression.

OpenStudy (zuha):

OpenStudy (zuha):

I believe the answer may be 10i+2/4?

OpenStudy (danjs):

hmm

OpenStudy (danjs):

you can look at it like the sum of two fractions like this.. \[\large \frac{ -5+i }{ 2i }=\frac{ -5 }{ 2i }+\frac{ i }{ 2i }\]

OpenStudy (danjs):

for a simpler form, you want to not have the i 's in the denominator.

OpenStudy (zuha):

So -5i/4? Or would it by 5/4?

OpenStudy (danjs):

remember -- \[i=\sqrt{-1}\] \[i^2=\sqrt{-1}*\sqrt{-1}=-1\]

OpenStudy (danjs):

multiply the first fraction by i / i , the second fraction, the i's cancel from top and bottom \[\frac{ -5 }{ 2i }*\frac{ i }{ i }+\frac{ 1 }{ 2 }\]

OpenStudy (danjs):

\[\large \frac{ -5i }{ 2i^2 }+\frac{ 1 }{ 2 } = \frac{ -5i }{ -2 }+\frac{ 1 }{ 2 } =\frac{ 5i }{ 2 }+\frac{ 1 }{ 2 } \]

OpenStudy (zuha):

Wait where did the i/i come from?

OpenStudy (danjs):

it is the same as multiplying something by 1, i/i=1, it is used to get rid of the i in the denominator

OpenStudy (zuha):

@DanJS How did the negatives go away int he second step? At −5i/-2+1/2?

OpenStudy (danjs):

-1/-1 = 1

OpenStudy (danjs):

negative divided by a negative is a positive

OpenStudy (zuha):

@DanJS Ah okay. So 5i/4?

OpenStudy (danjs):

how you get a 4 from the 2

OpenStudy (danjs):

\[\frac{ 5i }{ 2 }+\frac{ 1 }{ 2 }\]

OpenStudy (zuha):

@DanJS I was assuming we multiply them? Or do we leave it at 5i/2+1/2?

OpenStudy (zuha):

@DanJS

OpenStudy (danjs):

yeah i would leave it as it is now, in the form a + b*i

OpenStudy (zuha):

@DanJS Alright, thanks for your help! :)

OpenStudy (danjs):

welcome

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