Posted by Unknown. on Tuesday, August 21, 2012 at 9:43am.
Help?
I Kind of understand this , but still I am stuck.
1. (2+4i)/3i
2. 3√50 + 72
3.(4+√15)^2
4.4+√20
5.7√2(4√3)

Algebra2  ?  Steve, Tuesday, August 21, 2012 at 10:38am
we kind of don't know where you get stuck. Show us what you got, and we can help you work it the rest of the way.

Algebra2  Unknown., Tuesday, August 21, 2012 at 12:51pm
1. I got 6+3/10
but i don't believe that's the correct answer.
2. i got √21.21+√8.49
3. i got 34+14√10i
4. i got 1+√5i

Algebra2  Steve, Tuesday, August 21, 2012 at 1:10pm
#1: (2+4i)/(3i)
= (2+4i)(3+i) / (3i)(3+i)
= (6 + 12i + 2i + 4i^2) / (3^2  i^2)
= (6 + 14i  4) / (9+1)
= (2+14i)/10
= 1/5 + 7/5 i
#2: 3√50 + 72
3√50 i  72
3*5√2 i  72
72 + 15√2 i
in this kind of exercise, there's no call to approximate √ values with decimals. The √ is exact; the decimals are only an approximation.
#3: (4+√15)^2
= (4 + √15 i)^2
= (4)^2 + 2(4)(√15 i) + (√15 i)^2
= 16  8√15 i  15
= 1  8√15 i
#4: 4+√20
= 4 + √20 i
= 4 + 2√5 i
#5: 7√2(4√3)
= 7(√2 i)(4)(√3 i)
= 28 √6 i^2
= 28√6
Does that help? Just take these things step by step, keeping track of the i's and signs.
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