4=✓4²=✓16
2✓7=✓2²•7=✓4•7=✓28
✓28>✓16 → 2✓7>4
[tex] |4 - 2 \sqrt{7} | = - (4 - 2 \sqrt{7}) = \\ = - 4 + 2 \sqrt{7} = 2 \sqrt{7} - 4[/tex]
