Один вопрос алгебра ,,

1.
$y= \sqrt{x}-3 \\ y=0 \ \sqrt{x}-3=0 \\ \sqrt{x}-3=0 \\ x=3 \\ y=0 \\ x=0 \\ y=-3$

2.
$y=\mid\sqrt{x}-3\mid \\ y=0 \ x\ \textgreater \ 0 \\ \sqrt{x}+3=0 \\ x=9 \\ y=0\ x\ \textless \ 0 \\ -\sqrt{x}-3=0 \\ x=9 \\ x=0\ y= \pm{3}$

3.
$y=\sqrt{\mid{x}\mid}}-3 \\ y=0 \ x\ \textgreater \ 0 \\ \sqrt{\mid{x}\mid}}-3=0 \\ x=\pm{3} \\ y=0 \ x\ \textless \ 0 \\ x=\pm{3}$

4.
$y=\mid{\sqrt{\mid{x}\mid}}-3\mid} \\ y=0 x\ \textgreater \ 0 \\ x=\pm{3}$