Given expression is [tex]x^4-10x^2=-9[/tex]
Rearranging to get [tex]x^4-10x^2+9=0[/tex]
Let [tex]x^2[/tex] be [tex]p[/tex], then we have [tex]p^2-10p+9=0[/tex]
Factorising we get [tex](p-1)(p-9)=0[/tex]
Solving for [tex]p[/tex], we have [tex]p=1[/tex] and [tex]p = 9[/tex]
Rewriting [tex]p[/tex] back as [tex]x^2[/tex], we have:
[tex]x^2=1[/tex] and [tex]x^2=9[/tex]
[tex]x= \sqrt{1} [/tex] and [tex]x= \sqrt{9} [/tex]
[tex]x = (+1) and (-1)[/tex] and [tex]x=(+3) and (-3)[/tex] ⇒ Final answers
