[tex] x^{4} -32 x^{2} -144[/tex] will factor into the following
[tex]( x^{2} +4)( x^{2} -36)[/tex]
Set each factor equal to 0:
[tex] x^{2} +4=0 [/tex] or [tex] x^{2} -36=0[/tex]
[tex] x^{2} =-4[/tex] [tex] x^{2} =36[/tex]
x = +/- 2i x = +/- 6
Answer: 2i, 6, -6
