How to Solve a Quartic Equation by Hand

[phillyolly]

Hi!

I have been solving a problem and got an equation:
15x^4-30x^2+1=0

Do you know how to solve such equation for x by hand without using sophisticated math tools?

 

[The legend]

you can assume x^2 = t
so you get a quadratic in t... which i assume you can easily solve and get two values of t.
using these you will then get 4 values in x(some of which may be rejected according to the problem)

 

[phillyolly]

This is a great idea! Thank you! ;-)