Question 633063
9x^4+ 26x^2 = 3

let x^2=a

9a^2+26a-3=0

9a^2+27a-a-3=0

9a(a+3)-1(a+3)=0

(9a-1)(a+3)=0

either 9a-1=0 

OR

a+3=0

9a-1=0
resubstitute a
9x^2-1=0
(3x+1)(3x-1)=0

x= +/- 1/3

----
a+3=0
x^2+3=0
x^2=-3

x^2=-1*3

{{{x= sqrt(-1) * sqrt(3)}}}
x= +/-sqrt(3)i

x= +/- (1/3)