Answers

2014-05-19T13:17:40+05:30
Let  x^{2} =y
 y^{2} +5y+9=0

apply quadratic formual...
I think you equation is
 x^{4} +6 x^{2} +9=0
then,
y^{2}+6y+9=0
 y^{2}+3y+3y+9=0
 (y+3)(y+3)=0
 y=-3,-3
 x=i \sqrt{3} & i \sqrt{3}
(Note: i is iota)
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