I am to solve the equation: $|\frac{2x}{x^2 - 3} | < 1$ And so: 1. I rewrote it as $|2x| < |(x - \sqrt 3) | |(x + \sqrt 3)|$ And I tried to divide it into a few intervals
For $ x\in(-\infty;-\sqrt3)$
$-2x < (-x+\sqrt3)(-x-\sqrt3) \Rightarrow x\in(-\infty;-\sqrt3)$
For $x\in[-\sqrt3;0]$
$-2x < (-x+\sqrt3)(x+\sqrt3) \Rightarrow x\in(-1;0)$
For $x\in(0;\sqrt3]$
$2x < (-x+\sqrt 3)(x+\sqrt 3) => x\in(0;1)$
For $x\in(\sqrt3;\infty)$
$2x < (x-\sqrt3)(x+\sqrt3) \Rightarrow x\in(3;\infty)$
However, it looks as if some answers were missing. For exxample if I set $x=\sqrt2$, it still works, but I lack this answer. Where is my mistake?
$$\frac{4x^2}{(x^2-3)^2}\lt 1$$
$$4x^2\lt x^4-6x^2+9$$
$$x^4-10x^2+9>0$$
Put $y = x^2$
$$y^2-10y+9>0$$
$$(y-9)(y-1)>0$$
$$y>9 = x^2>9$$ $$=>x>3 \text{ and } x<-3$$
and $$y<1$$
$$=>x^2<1=>$$ $$ x<1 \text{ and }x>-1 $$
The solution to the problem is
$$x\epsilon {(-\infty,-3),(-1,1),(3,\infty)}$$