[tex]6 \sqrt{2} = \sqrt{6 {}^{2} \times 2 } = \sqrt{36 \times 2} = \sqrt{72} [/tex]
[tex]4 \sqrt{5} = \sqrt{4 {}^{2} \times 5 } = \sqrt{16 \times 5} = \sqrt{80} [/tex]
[tex]5 \sqrt{3} = \sqrt{5 {}^{2} \times 3 } = \sqrt{25 \times 3} = \sqrt{75} [/tex]