Harvard University Admission Aptitude Test || Algebra Entrance Exam || Find x ?

[@2012tulio]

X={3.3027; -0.3027}

[@prollysine]

let x-1/x=u , u^3+u=30 , u^3+u-30=0 , by faktor. , add -3u^2 , 3u^2 , u^3-3u^2 +3u^2-9u +10u-30=0 , (u-3)(u^2+3u+10)=0 , u=3 , x-1/x=3 , x^2-3x-1=0 , x= (3+V13)/2 , (3-V13)/2 , /// for complex , u^2+3u+10=0 , u=(-3 +/- V(9-40))/2 , u=(-3 +/- i*V31)/2 , x-1/x= (-3 + i*V31)/2 , (-3 - i*V31)/2 , ///

[@RamendraPaswan-f2k]

X-1/x=k(माना)