Posted by swirl on Saturday, July 9, 2011 at 9:52pm.
sqrt -8 = i sqrt 8 = 2 sqrt 2 i sqrt -24 = i sqrt 24 = i sqrt(8*3) = 2i sqrt2 sqrt3 so 2 i sqrt2 * 2 i sqrt2 sqrt3 = -4*2 sqrt 3 = -8 sqrt 3