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Mathematics 16 Online
OpenStudy (anonymous):

Simplify. 2 + 4i/3i

OpenStudy (anonymous):

simplify my eye! it means "divide and write an standard form there is no such mathematical operation as "simplify"

OpenStudy (anonymous):

i assume it is \[\frac{2+4i}{3i}\] right?

OpenStudy (anonymous):

yeup!

OpenStudy (anonymous):

multiply top and bottom by \(i\)

OpenStudy (anonymous):

then there will be no \(i\) in the denominator let me know what you get

OpenStudy (anonymous):

\[\frac{ 2i-4 }{-3 }\]

OpenStudy (anonymous):

@satellite73

OpenStudy (anonymous):

ok good one step away from writing in standard form

OpenStudy (anonymous):

\[\frac{2i-4}{-3}=\frac{4}{3}-\frac{2}{3}i\]

OpenStudy (anonymous):

good with that?

OpenStudy (anonymous):

would I simplify this the same way? \[\frac{ 3+2i }{ 4+i }\]

OpenStudy (anonymous):

no

OpenStudy (anonymous):

if you multiply top and bottom by \(i\) you will still have an \(i\) in the denominator, it will just change places

OpenStudy (anonymous):

you have to multiply top and bottom by the "conjugate" of the denominator the conjugate of \(a+bi\) is \(a-bi\) and this works because \[(a+bi)(a-bi)=a^2+b^2\] a real number

OpenStudy (anonymous):

When I used FOIL to multiply it I got \[\frac{ 12-3i+8i-2i ^{2} }{ 16-4i-i ^{2}+4i }\]

OpenStudy (anonymous):

ok don't forget that \((a+bi)(a-bi)=a^2+b^2\) so your denominator should be \(4^2+1^2=17\)

OpenStudy (anonymous):

which is in fact what you have, just too much work

OpenStudy (anonymous):

oh OK so now I got \[\frac{ 14+5i }{ 17 }\] is that it? or can we do more to that?

OpenStudy (anonymous):

if you want it in standard for you write it as \[\frac{14}{17}+\frac{5}{17}i\]

OpenStudy (anonymous):

"standard forM"

OpenStudy (anonymous):

alright I got it :)

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