Algebra
posted by Katie .
4x^418x^2=0. I have to find out what x equals by factoring. What I did was
Factor 2x^2(2x^2+9)=0 then 2x^2(2x+3)(x+3), resulting in 1.5 and three. But these answers are wrong according to my book. Can you show me step by step how to do this correctly? It would be a huge help!

They are wrong.
2x^2(2x^29)=0
2x^2(xsqrt23)(xsqrt2+3)=0
so the roots are 0,0,3/sqrt2, 3/sqrt2) 
Why did you square root the second line? Would you please be able to explain? Thanks!