Question

Stiind ca x+1/x=3 , x inclus R* calculati x la a doua +1/x la a doua. Raspunsul este?

Answer 1

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