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f-x-1-x-x-6-1-27-f-x-




Question Number 78794 by naka3546 last updated on 20/Jan/20
f(x + (1/x))  =  ((x^6  + 1)/(27))  f(x)  =  ...
f(x+1x)=x6+127f(x)=
Answered by mr W last updated on 20/Jan/20
t=x+(1/x)  x^2 −tx+1=0  ⇒x=(1/2)(t±(√(t^2 −4)))  x^2 =tx−1  x^3 =tx^2 −x=t(tx−1)−x=(t^2 −1)x−t  x^6 =(t^2 −1)^2 x^2 −2t(t^2 −1)x+t^2   x^6 =(t^2 −1)^2 (tx−1)−2t(t^2 −1)x+t^2   x^6 =t(t^2 −3)[(t^2 −1)x−t]−1  x^6 +1=t(t^2 −3)[(t^2 −1)x−t]  ((x^6 +1)/(27))=((t(t^2 −3))/(27))[(((t^2 −1)(t±(√(t^2 −4))))/2)−t]  f(t)=((t(t^2 −3))/(27))[(((t^2 −1)(t±(√(t^2 −4))))/2)−t]  ⇒f(x)=((x(x^2 −3))/(27))[(((x^2 −1)(x±(√(x^2 −4))))/2)−x]
t=x+1xx2tx+1=0x=12(t±t24)x2=tx1x3=tx2x=t(tx1)x=(t21)xtx6=(t21)2x22t(t21)x+t2x6=(t21)2(tx1)2t(t21)x+t2x6=t(t23)[(t21)xt]1x6+1=t(t23)[(t21)xt]x6+127=t(t23)27[(t21)(t±t24)2t]f(t)=t(t23)27[(t21)(t±t24)2t]f(x)=x(x23)27[(x21)(x±x24)2x]

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