Write the biquadratic equation in the form (ax^4+bx^2+c=0)
Substitute (y=x^2)
Solve the quadratic equation (ay^2+by+c=0)
Find the roots (y_1) and (y_2)
Set (x^2=y_1) and solve for (x)
Set (x^2=y_2) and solve for (x)
Include both positive and negative square roots for each valid (y)
Discard any roots that give negative values under the square root when working over the real numbers
Verify the obtained roots by substituting them back into the original equation