0\; \to \; |x|=x\; \to \\\\\sqrt{x^4-4x^2+4} \leq 1\\\\0 \leq x^4-4x^2+4 \leq 1\\\\x^4-4x^2+3 \leq 0\; \; \to \; \; x^2=1\; \; ili\; \; x^2=3\\\\x=\pm 1\; \; ili\; \; x=\pm \sqrt3" alt="\sqrt{x^4-4\cdot |x|\cdot x+4} \leq \frac{x}{|x|}\; \; ;\; \ ; ODZ:\; \; x\ne 0,\; x\in (-\infty,0)U(0,+\infty)\\\\a)\; x<0\; \to \; |x|=-x\; \to \\\\\sqrt{x^4+4x^2+4} \leq -1\; \; nevozmozno,\; t.k. \; \sqrt{x^4+4x^2+4} \geq 0\\\\b)\; x>0\; \to \; |x|=x\; \to \\\\\sqrt{x^4-4x^2+4} \leq 1\\\\0 \leq x^4-4x^2+4 \leq 1\\\\x^4-4x^2+3 \leq 0\; \; \to \; \; x^2=1\; \; ili\; \; x^2=3\\\\x=\pm 1\; \; ili\; \; x=\pm \sqrt3" align="absmiddle" class="latex-formula">