Question

Daca

$x^{2} + \frac{1}{ x^{2} } =83 , calculati    x- \frac{1}{x}$

Answer 1

x²+1/x²=83
(x-1/x)²=x²-2×x×1/x+1/x²=x²-2+1/x²=x²+1/x²-2=83-2=81
x-1/x =√81
x-1/x =+9
x-1/x =-9