Respuesta :

LammettHash

Recall that

[tex](a+b)^2=a^2+2ab+b^2[/tex]

So we have

[tex]\left(x+\dfrac1x\right)^2=x^2+2+\dfrac1{x^2}[/tex]

Given that [tex]x+\frac1x=5[/tex], we get

[tex]x^2+\dfrac1{x^2}=5^2-2=\boxed{23}[/tex]

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