If x2+frac1x2=7x^2 + \\frac{1}{x^2} = 7x2+frac1x2=7, find x−frac1xx - \\frac{1}{x}x−frac1x (take positive root).
sqrt5\\sqrt{5}sqrt5
333
sqrt9\\sqrt{9}sqrt9
sqrt7\\sqrt{7}sqrt7