0\; pri\; x\in R,\; t.k.\; D<0\\\\x=-1" alt="\Delta =0\\\\\Delta=x \left|\begin{array}{ccc}1&x\\x&-2\\\end{array}\right| -x \left|\begin{array}{ccc}x&x\\x&-2\\\end{array}\right| +x \left|\begin{array}{ccc}x&1\\x&x\\\end{array}\right| =\\\\=-2x-x^2-x(-2x-x^2)+x(x^2-x)=2x^3+2=0\\\\2(x^3+1)=0\\\\2(x+1)(x^2-x+1)=0\\\\x^2-x+1>0\; pri\; x\in R,\; t.k.\; D<0\\\\x=-1" align="absmiddle" class="latex-formula">