replace x^2 with m and try to solve
-3 m^2 +27 m +1200 =0
factor out -3
-3(m^2 -9m-400)=0
-3 (m-25) (m+16) =0
using the zero product property
m-25 =0 m+16=0
m=25 m=-16
then substitute m=x^2 back in
x^2 = 25 x^2 = -16
x take the square root of each side
x = +- sqrt (25) if you know complex number x = +- sqrt (-16)
x = +-5 x = +- 4i
Answer: +5, -5 , +4i, -4i
