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Mathematics 12 Online
OpenStudy (anonymous):

2-5i/3i

OpenStudy (anonymous):

\[\frac{ 2-5i }{ 3i }\]

OpenStudy (anonymous):

I understand you are supposed to multiply by the conjugate, but what is the conjugate of 3i

OpenStudy (anonymous):

@Hero @nincompoop

zepdrix (zepdrix):

The conjugate of \(\large\rm 0+3i\) is \(\large\rm 0-3i\)

zepdrix (zepdrix):

So therefore the conjugate of \(\large\rm 3i\) is simply \(\large\rm -3i\) k? :)

OpenStudy (anonymous):

don't be a slave to method you can multiply by \(i\) top and bottom if you like or \(-i\)

zepdrix (zepdrix):

Ya that'll save you a couple steps :D Seems like a good idea

OpenStudy (anonymous):

either way the denominator will become a real number, either 3 or -3 depending on which you pick

OpenStudy (anonymous):

I see thank you so much

OpenStudy (anonymous):

Wait, I get a different answer from when i multiply -3i to when i multiply from just i

OpenStudy (anonymous):

not after you cancel the common factor of 3

OpenStudy (anonymous):

which is why multiplying by \(-3i\) is silly in this case

OpenStudy (anonymous):

ohhh so should the final answer be -2i -5

OpenStudy (anonymous):

idk i didn't do it want me to check?

OpenStudy (anonymous):

yes please

OpenStudy (anonymous):

no actually that can't be it

OpenStudy (anonymous):

\[\frac{ 2-5i }{ 3i }\times \frac{i}{i}\] \[=\frac{2i+5}{-3}\]

OpenStudy (anonymous):

i got -6i -15 but then factored out 3

OpenStudy (anonymous):

yes but my answer has to be in complex number form i'm sorry i forgot to mention that

OpenStudy (anonymous):

now i am confused @satellite73 @zepdrix

OpenStudy (anonymous):

you mean in the form \(a+bi\)?

OpenStudy (anonymous):

yes

OpenStudy (anonymous):

break it in to two pieces is all

OpenStudy (anonymous):

for example \[\frac{7+8i}{5}=\frac{7}{5}+\frac{8}{5}i\]

OpenStudy (anonymous):

oh i understand now can i get back to you in a minute with my answer?

OpenStudy (anonymous):

is this correct? \[\frac{ 2i }{ -3 }+\frac{ 5 }{ -3 }\]

OpenStudy (beginnersmind):

Yes, although you might want to write it as \[-\frac{ 5 }{ 3 } -\frac{ 2 }{ 3 }i\] or even \[\frac{ -5-2i }{ 3 }\] but it's just cosmetical at this point.

OpenStudy (anonymous):

thank you so much

OpenStudy (beginnersmind):

No problem, satellite did all the work though. ;)

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