Question

x+1/x=3 x*+1/x*=?
* = la a doua

Answer 1

$(x+ \frac{1}{x} )^{2} = x^{2} +2*x* \frac{1}{x} + \frac{1}{ x^{2} } = x^{2} + \frac{1}{ x^{2} } +2 \\ 3^{2} =x^{2} + \frac{1}{ x^{2} } +2 \\ x^{2} + \frac{1}{ x^{2} }=9-2=7$