Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
yes, the second one
OpenStudy (anonymous):
how did you arrive at 4?
OpenStudy (anonymous):
-4*
OpenStudy (anonymous):
it's not \[\frac{ -4 }{ 4-5i }\]
OpenStudy (anonymous):
4i
Still Need Help?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
\[\frac{ 4i }{ 4-5i }\] altough it's possible to simplify it further
OpenStudy (anonymous):
multiply everything by the conjugate of the denominator
OpenStudy (anonymous):
yes
OpenStudy (anonymous):
the final answer still has an i in it
OpenStudy (anonymous):
\[\frac{ 4i(4+5i) }{ (4-5i)(4+5i) }\]
Still Need Help?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
close, but one important detail
OpenStudy (anonymous):
i*i=i²
and since i=\(\sqrt{-1}\) then i²=-1
OpenStudy (anonymous):
41 is correct, double minus is plus
OpenStudy (anonymous):
answer is correct too. although you should probably write it \[\frac{ 4 }{ 41 }*(4i-5)\]
OpenStudy (anonymous):
alright, no problem
Still Need Help?
Join the QuestionCove community and study together with friends!
Sign Up
OpenStudy (anonymous):
by the way, i may be mistaken on this, but i am pretty sure if you multiply a complex number with it's own conjugate, you can just take the square of both numbers and add them.
for example with (4i-5)(4i+5) = 5²+4² i'm not sure if this trick always works, but i'm 99% sure it does.
OpenStudy (anonymous):
i meant (4-5i)(4+5i) obviously
OpenStudy (anonymous):
i just used my calculator to check if that rule is always true, and it is.