Объяснение:

[tex] \sqrt{90 \times 490} = \sqrt{9 \times 10 \times 49 \times 10} = 3 \times 7 \times 10 = 210[/tex]

[tex] \sqrt{72 \times 32} = \sqrt{36 \times 2 \times 16 \times 2} = 6 \times 4 \times 2 = 48[/tex]

[tex] \sqrt{4.9 \times 32.4} = \sqrt{49 \times 0.1 \times 324 \times 0.1} = 7 \times 18 \times 0.1 = 12.6[/tex]

[tex] \sqrt{4.5 \times 72} = \sqrt{9 \times 0.5 \times 144 \times 0.5} = 3 \times 12 \times 0.5 = 18[/tex]

[tex] \sqrt{13} \times \sqrt{3} \times \sqrt{39} = \sqrt{39} \times \sqrt{39} = 39[/tex]

[tex] \sqrt{22} \times \sqrt{14} \times \sqrt{77} = \sqrt{11 \times 2} \times \sqrt{7 \times 2} \times \sqrt{7 \times 11} = 11 \times 7 \times 2 = 154[/tex]

[tex]( \sqrt{11} + \sqrt{7} )( \sqrt{11} - \sqrt{7} ) = { \sqrt{11} }^{2} - { \sqrt{7} }^{2} = 11 - 7 = 4[/tex]

[tex](2 - \sqrt{3} )(2 + \sqrt{3} ) = {2}^{2} - { \sqrt{3} }^{2} = 4 - 3 = 1[/tex]

[tex] \sqrt{2} ( \sqrt{8} - \sqrt{72} ) = \sqrt{16} - \sqrt{144} = 4 - 12 = - 8[/tex]

[tex](2 \sqrt{3} - \sqrt{27} + \sqrt{48} ) \sqrt{3} = 2 \sqrt{9} - \sqrt{81} + \sqrt{144} = 2 \times 3 - 9 + 12 = 6 - 9 + 12 = 9[/tex]

[tex](2 + \sqrt{3} )(1 - \sqrt{3} ) = 2 + \sqrt{3} - 2 \sqrt{3} - \sqrt{9} = 2 - \sqrt{3} - 3 = - 1 - \sqrt{3} [/tex]

[tex](3 - \sqrt{5} )(1 + \sqrt{5} ) = 3 - \sqrt{5} + 3 \sqrt{5} - \sqrt{25} = 3 + 2 \sqrt{5} - 5 = 2 \sqrt{5} - 2[/tex]