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Mathematics 15 Online
OpenStudy (danielbarriosr1):

Please help me simplify

OpenStudy (danielbarriosr1):

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

OpenStudy (anonymous):

god help me they call everything "simplify" what they mean is "write in standard from as \(a+bi\)" tell your math teacher !

OpenStudy (danielbarriosr1):

Now everything makes sense

OpenStudy (anonymous):

\[\frac{ 3-i }{ 2+5i}\times \frac{2-5i}{2-5i}\] is a start

OpenStudy (danielbarriosr1):

the conjugate right?... I don't know if thats how you spell it

OpenStudy (danielbarriosr1):

to eliminate the i in the bottom

OpenStudy (anonymous):

i.e. multiply 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):

on your case you will have \[\frac{(3-i)(2-5i)}{2^2+5^2}\] all the work is now in the numerator

OpenStudy (anonymous):

yeah that is how you spell it too

OpenStudy (anonymous):

you got the top?

OpenStudy (danielbarriosr1):

yeah that would be \[\frac{ 4-10i }{ 4-25i^2 }\]

OpenStudy (danielbarriosr1):

right? @satellite73

OpenStudy (danielbarriosr1):

My bad, I mean \[\frac{ 1-17i }{ 4-25i^2 }\]

OpenStudy (danielbarriosr1):

right? @satellite73

OpenStudy (misty1212):

\[(a+bi)(a-bi)=a^2+b^2\] so \[(2+5i)(2-5i)=2^2+5^2=4+25=29\]

OpenStudy (misty1212):

dont mess around with any \(i\) stuff when you multiply by the conjugate

OpenStudy (danielbarriosr1):

all right so it would be \[\frac{ 1 }{ 29 }-\frac{ 17i }{ 29 }\]

OpenStudy (danielbarriosr1):

right? @misty1212

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