Mathematics
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OpenStudy (anonymous):
Solve:
(2-3i)(5i)/ 2+3
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OpenStudy (lalaly):
complex?
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
I don't think that's it. You have to use the conjugate of the bottom
OpenStudy (anonymous):
oh.
OpenStudy (lalaly):
\[\frac{(2 \times 5i)-(3i \times 5i)}{5}= \frac{10i - 15i^2}{5}\]\[i=\sqrt{-1} ... i^2=-1\]\[\frac{10i-15(-1)}{5}= \frac{10i+15}{5} = 2i+3\]
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OpenStudy (anonymous):
Distibute the top, and then deal with the bottom. There isn't any subtraction sign in the top part
OpenStudy (lalaly):
the bottom is 2+3 which is 5
and i already distributed whats in the numerator
OpenStudy (anonymous):
2 plus 3 "I"
OpenStudy (lalaly):
oh u forgot the i
OpenStudy (anonymous):
Sorry :O
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OpenStudy (anonymous):
Why 2-9?
OpenStudy (lalaly):
3i*3i = -9
in the denominator
OpenStudy (anonymous):
on the bottom I got 4-9i and then that =13
OpenStudy (anonymous):
and why is 20i not -20i
OpenStudy (lalaly):
yeah that was my mistake im sorry ... difference between two squares (2-3i)(2+3i)=4-(-9)
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OpenStudy (lalaly):
wait let me do it again
OpenStudy (anonymous):
yes, it is a positive 20, my bad :D
OpenStudy (anonymous):
wait no, take back!
OpenStudy (lalaly):
\[\frac{10i+15}{2+3i} \times \frac{2-3i}{2-3i} = \frac{20i-30(-1)+30-45i}{4-(-9)}\]\[=\frac{-25i+60}{13}\]
OpenStudy (anonymous):
When you multiply the -10 and the 2i should it be -20i
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OpenStudy (lalaly):
what -10 and 2i?
OpenStudy (lalaly):
thers 10i and 2
OpenStudy (anonymous):
but the 10 is negative?
OpenStudy (lalaly):
no when u distribute at the begining 5i*2 = 10i
OpenStudy (anonymous):
I am going to attach my work
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OpenStudy (lalaly):
kk
OpenStudy (anonymous):
can in progress. sorry
OpenStudy (anonymous):
*scan
OpenStudy (lalaly):
well the solution for \[\frac{(2-3i)(5i)}{2+3i}\]is what i did , last thing
OpenStudy (anonymous):
Thanks