If x is positive, which of the following could be correct ordering of \(\frac{1}{x}\), \(2x\), and \(x^2\)?
I. \(x^2 < 2x < \frac{1}{x}\)
x^2 - 2x < 0; x(x-2)<0; 0<x<2
2x - 1/x < 0; (2x^2 - 1)/x < 0; Since x>0; 2x^2 - 1< 0; x^2 < 1/2; \(x < 1/\sqrt{2}\)
For\( 0<x<\frac{1}{\sqrt{2}}\), Possible
II. \(x^2 < \frac{1}{x} < 2x\)
x^2 - 1/x < 0; (x^3 - 1)/x < 0; x^3 - 1 < 0; (x-1)(x^2 + x + 1) < 0; x < 1 since (x+1/2)^2 + 3/4 > 0
1/x - 2x < 0; (1 - 2x^2)/x < 0; x^2 > 1/2; \(x > \frac{1}{\sqrt{2}}\)
\(\frac{1}{\sqrt{2}} < x < 1\); Possible
III. \(2x < x^2 < \frac{1}{x}\)
2x - x^2 < 0; x(x-2) > 0; x > 2
x^2 - 1/x < 0
(x^3 -1)/x < 0; (x-1)(x^2 + x + 1) < 0; x < 1 since (x+1/2)^2 + 3/4 > 0
Not possible since x < 1 & x> 2 is not possible simultaneously
(A) none
(B) I only
(C) III only
(D) I and II
(E) I, II and III
IMO D