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Mathematics 21 Online
OpenStudy (anonymous):

Algebra 2 Help!

OpenStudy (anonymous):

\[\large 6\sqrt[3]{2}\]

OpenStudy (anonymous):

\[ \huge 3\sqrt[3]{16}=3\sqrt[3]{2^{4}}=3*2^{\frac{ 4 }{ 3 }}=\] \[\huge 3*2^{\frac{ 3 }{ 3 }}*2^{\frac{ 1 }{ 3 }} =3*2*\sqrt[3]{2} \]

OpenStudy (anonymous):

you're welcome

OpenStudy (anonymous):

sure

OpenStudy (anonymous):

bottom

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

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):

\[\frac{ 4i(4+5i) }{ (4-5i)(4+5i) }\]

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

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.

OpenStudy (anonymous):

(a+bi)(a-bi)=a²+b²

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