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[tex] x^{2} + \frac{1}{ x^{2} } =83 , calculati    x- \frac{1}{x} [/tex]


Răspuns :

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