Question 28263
3U^2+40=4
3U^2=4-40
3U^2=-36
U^2= -36/3
U^2= -12 0r U^2 = 12x(-1)  replace -1 by i^2
U^2= 12i^2
U= + and - square root of 12i^2
The answers are:
u= +2i √3
u= -2i √3