Question

                         1
se stie ca  x +  ---   =  2013
                         x
                            
                             1
calculati    x² +    ---
                             x²

Answer 1

Ridici la patrat fiecare membru al egalitatii tale => x^2 + 1 / x^2 + 2*x*( 1 / x ) = 2013^2 <=>  x^2 + 1 / x^2 = 2013^2 - 2

Bafta!