Question

I got the answer for x^2/4 + 4=0 but the answer was
4i, 4i what does that mean?

Answer 1

http://en.wikipedia.org/wiki/Imaginary_number

Answer 2

i is a number with property i²=-1, or \(i=\sqrt{-1}\)

If you solve \(\dfrac{x^2}{4}+4=0\), you get \(\dfrac{x^2}{4}=-4\), so \(x^2=-16\).

Then \(x=\pm \sqrt{-16}=\pm \sqrt{16}\cdot\sqrt{-1}=\pm 4i\).

Answer 3

If you are supposed to give answers like this (instead of: the given eqn. has no (real) solutions), I assume you have learned about these "imaginary numbers"...