Algebra2
posted by Unknown. on .
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)

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.

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 
#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.