Question

Find all real solutions of the equation exactly 6z^4-13z^2+5=0

Answer 1

6z^4-13z^2+5=0
6z^4-10z^2-3z^2+5=0
3z^2(2z^2-5)-1(2z^2-5)=0
(2z^2-5)((3z^2-1)=0
so either (2z^2-5)=0 or (3z^2-1)=0
z^2=5/2 or z^2=1/3

z=5/2 or z=-5/2 or z=1/3 or z=-1/3