Algebra2
posted by Tara on .
I got this answer for a problem, and I'm not sure if it's right.
Can someone tell me if I'm correct?
1.(2+4i / 3i)
= 6/7+5/7i

2+41 /(3i)
rationalize
(2+4i)(3+i)/10= (6+2i+12i4)/10=
=(2+14i)/10 
Ahh!
I'm confused about this math stuff:/
it's my first time trying these algebra problems.
I'm trying to go by the teacher's examples.
Can You tell me if these are right:p?
2. (7√15)^2
= 34+14i√15i
3.4+√20 / 2
=2+2.5√4i 
another way, in polar form:
(2+4i)=sqrt20@arctan2
(3i)=sqrt10@arctan(1/3)
so (2+4i)/(3i)=sqrt20/sqrt10 @ (arctan2arctan1/3)=sqrt2 @(1.11rad(.321))
= sqrt2 @1.43rad=sqrt2 @ 81.9 deg
Now converting this (only to compare with the above)
= sqrt2 (cos81.9+isin81.9)
= (.198+i*1.40)
and the above is .2+i1.40
I rounded the angles on the arctan conversions... 
2. (7√15)^2
= 34+14i√15i ????
(7isqrt15)^2=49152isqrt15=342i sqrt15
3.4+√20 / 2
=2+2.5√4i ????
4/2+1/2 i sqrt20=2+.5i*sqrt4*sqrt5
= 2+i sqrt5 
(7isqrt15)^2=49152isqrt15??
I get 4915 14√15 i