Question

which is equal to 2 sqrt -27?
A. 6 sqrt 3
B. -6 sqrt 3
C. -6i sqrt 3
D. 6i sqrt 3

Answer 1

Any ideas?

Answer 2

i'm usually pretty good with math, and don't normally ask questions, but i absolutely don't understand the concept of imaginary numbers. i take an online math class, so the explanation is pretty vague... so no, no ideas at all :(

Answer 3

By definition i^2 = -1.

Answer 4

okay, so how does that apply to the radical?

Answer 5

like how would I solve it?

Answer 6

\[i^2=-1\]\[i=\sqrt{-1}\]
\[\sqrt{-27}=\sqrt{27*(-1)}=\sqrt{9*(-1)*3}=\sqrt{9*i^2*3}=3i\sqrt{3}\]

Answer 7

wouldn't it be 6i sqrt 3?

Answer 8

I was only doing sqrt(-27) to illustrate how to evaluate the radical, your problem is 2 sqrt(-27). Had to leave some of the work for you :-)

Answer 9

i figured it out after :) thank you

Answer 10

Trivia factoid for the night: electrical engineers make extensive use of imaginary numbers, but they don't use i — they use j instead :-) Same value. i gets used for current.

Answer 11

More useful bit of trivia: \[e^{i\pi}+1=0\]How cool is that?