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OpenStudy (gabylovesyou):
\[\frac{ \sqrt{-25} }{ (5-2i) + (1-3i) }\]
OpenStudy (gabylovesyou):
@jhonyy9 @ikram002p
OpenStudy (gabylovesyou):
@freckles
OpenStudy (gabylovesyou):
is it \[\frac{ -25 +30i }{ 61 }\]
jhonyy9 (jhonyy9):
sqrt(-25)
−−−−-------- =
(5−2i)+(1−3i)
how you have got it ?
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jhonyy9 (jhonyy9):
sqrt(-25) = 5i
yes ?
OpenStudy (gabylovesyou):
cuz i first got
\[- \frac{ 5(5-6i) }{ 61 }\]
OpenStudy (gabylovesyou):
idk how to simplify that..
jhonyy9 (jhonyy9):
let 5-2i = a
and 1-3i = b
so than in denominator there are a+b
but you know what mean conjugate of something ?
OpenStudy (gabylovesyou):
yes.. to turn the symbol around.. so instead of - its +
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jhonyy9 (jhonyy9):
hope you know formula a^2 -b^2 = (a-b)(a+b)
OpenStudy (gabylovesyou):
i do
jhonyy9 (jhonyy9):
than multiplie down and up by a-b - what will get ?
OpenStudy (gabylovesyou):
what do you mean ?
jhonyy9 (jhonyy9):
check what i have wrote above
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OpenStudy (gabylovesyou):
im confused.
OpenStudy (gabylovesyou):
i dont understand what i have to do
jhonyy9 (jhonyy9):
(5−2i)+(1−3i) - this is the denominator
a + b
than multiplie down and up by a-b so you will get a^2 -b^2
what mean a^2 =(5-2i)^2 and
b^2 = (1-3i)^2
yes ?
OpenStudy (gabylovesyou):
yes i understand .
jhonyy9 (jhonyy9):
distribute parentheses -- see what will get - remain in denominator - what you need to make - try eliminate the terms with i from denominator
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OpenStudy (phi):
it looks a bit painful.
I would first add the bottom: reals to reals and imaginary to imaginary to get 1 complex number
can you do that ?
OpenStudy (gabylovesyou):
you mean like 6 - 5i ?
OpenStudy (gabylovesyou):
@phi
jhonyy9 (jhonyy9):
yes - so will be more easy
jhonyy9 (jhonyy9):
so than with 6-5i multiplie numerator and denominator by conjugate of 6-5i
do you know it ?
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OpenStudy (gabylovesyou):
conjugate is 6 +5i but what do i multiply it with ?
OpenStudy (phi):
yes
jhonyy9 (jhonyy9):
(6-5i)(6+5i) = ?
OpenStudy (gabylovesyou):
61?
jhonyy9 (jhonyy9):
yes
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OpenStudy (phi):
you multiply top and bottom by the conjugate 6+5i
the bottom is 36+25 = 61 (looks like that is what you got before)
the top is 5i(6+5i) = -25 +30i
jhonyy9 (jhonyy9):
so this will get for denominator
OpenStudy (phi):
it looks like you did it correctly up top
OpenStudy (gabylovesyou):
soo the answer is correct.. its \[\frac{ -25 + 30i }{ 61 }\]
OpenStudy (gabylovesyou):
ok thank you
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OpenStudy (phi):
sometimes, people write it as -25/61 + 30/61 i
so that it is in real/imag format