[tex]\bold3.\\-x^2+12>0\\-x^2>-12|\cdot(-1)\\x^2<12\\-\sqrt{12}<x<\sqrt{12}\\-2\sqrt3<x<2\sqrt3[/tex]
[tex]\bold4.\\x^2\leqslant16\\-4\leqslant x\leqslant4[/tex]
[tex]\bold5.\\x^2 \geqslant 36\\x\leqslant -6~~~~\vee~~~~x\geqslant 6[/tex]
[tex]\bold6.\\x^2+49>0|-49\\x^2>-49\\x\in Q[/tex]
[tex]\bold7.\\-x^2+1 \leqslant 0\\-x^2 \leqslant -1|\cdot(-1)\\x^2 \geqslant 1\\x \leqslant-1~~~~\vee~~~~x\geqslant1[/tex]
[tex]\bold8.\\x^2-x>0\\\text{Rozwiazujemy najpierw rownanie, nastepnie}\\\text{przejdziemy do rozwiazania nierownosci}\\x^2-x=0\\x(x-1)=0\\x=0~~~~\vee~~~~x-1=0\\~~~~~~~~~~~~~~~~~~~x=1\\x^2-x>0\\x<0~~~~\vee~~~~x>1[/tex]
[tex]\bold9.\\x^2+2x<0\\\\x^2+2x=0\\x(x+2)=0\\x=0~~~~\vee~~~~x+2=0\\~~~~~~~~~~~~~~~~~~~x=-2\\x^2+2x<0\\-2<x<0[/tex]
[tex]\bold{10}.\\2x^2\geqslant x|-x\\2x^2 -x\geqslant 0\\\\2x^2-x=0\\x(2x-1)=0\\x=0~~~~\vee~~~~2x-1=0\\~~~~~~~~~~~~~~~~~~~2x=1|:2\\~~~~~~~~~~~~~~~~~~~x=\frac12\\2x^2 \geqslant x\\x\leqslant0~~~~\vee~~~~x\geqslant\frac12[/tex]
