[tex] \tt = 6 \sqrt{72} - \sqrt{18} - 8 \sqrt{32} \\ \tt= 6 \sqrt{36 \times 2} - \sqrt{9 \times 2} - 8 \sqrt{16 \times 2} \\ \tt = 6 \sqrt{ {6}^{2} \times 2 } - \sqrt{ {3}^{2} \times 2} - 8 \sqrt{ {4}^{2} \times 2} \\ \tt = 6 \times 6 \sqrt{2} - 3 \times 1\sqrt{2} - 8 \times 4 \sqrt{2} \\ \tt = 36 \sqrt{2} - 3 \sqrt{2} - 32 \sqrt{2} \\ \tt = \sqrt{2} (36 - 3 - 32) \\ \tt = \sqrt{2} (36 - 35) \\ \tt = \sqrt{2} (1) \\ \tt \red{ \boxed{= \sqrt{2}}} .. \green{is \: the \: answer..}[/tex]

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