Odpowiedź :
[tex]\sqrt{72} +4\sqrt{2} -\sqrt{18} +\sqrt{8} =\sqrt{36 \cdot 2} +4\sqrt{2} -\sqrt{9 \cdot 2} +\sqrt{4 \cdot 2} =6\sqrt{2} +4\sqrt{2} -3\sqrt{2} +2\sqrt{2} =10\sqrt{2} -\sqrt{2} =9\sqrt{2}[/tex]
[tex]\sqrt{72} +4\sqrt{2} -\sqrt{18} +\sqrt{8} =\sqrt{36\cdot 2} +4\sqrt{2}-\sqrt{9\cdot 2} +\sqrt{4\cdot 2} =\sqrt{6^{2} \cdot 2} +4\sqrt{2}-\sqrt{3^{2} \cdot 2} +\sqrt{2^{2} \cdot 2} =6\sqrt{2} +4\sqrt{2} -3\sqrt{2} +2\sqrt{2} =\sqrt{2} \cdot (6+4-3+2)=\sqrt{2} \cdot 9=9\sqrt{2}[/tex]