Answer:
1) [tex]y=(x-3)(x+3)(x-1)(x+1)[/tex]
2) [tex]x=3,\:x=-3,\:x=1,\:x=-1[/tex]
Step-by-step explanation:
Factor by grouping
[tex]y=x^4-10x^2+9\\\\y=x^4-x^2-9x^2+9\\\\y=x^2(x^2-1)-9(x^2-1)\\\\y=(x^2-9)(x^2-1)\\\\y=(x-3)(x+3)(x-1)(x+1)[/tex]
Solutions
[tex]y=(x-3)(x+3)(x-1)(x+1)\\\\0=(x-3)(x+3)(x-1)(x+1)\\\\x=3,\:x=-3,\:x=1,\:x=-1[/tex]