+0

# imaginary numbers

+1
139
2
+532

im thinking for this one it might be 6i sqrt 3

but im not sure i could be wrong

my guess is -i for this question

Sep 8, 2018

#1
+67
+1

I dont know the first one but the second one is just -i

Sep 8, 2018
#2
+4490
+2

-i is correct though it would be better if you understood why.

$$\forall n \in \mathbb{Z} \\ i^{4n} = 1 \\ i^{4n+1}=i \\ i^{4n+2}=-1 \\ i^{4n+3}=-i$$

for the first problem we have

$$2\sqrt{-27} = 2\sqrt{27}\sqrt{-1} = 6\sqrt3 i = 6i \sqrt{3}$$

the 3rd choice

Sep 8, 2018