Объяснение:

1

а)

[tex] \sqrt{640 \times 160} = \sqrt{64 \times 10 \times 16 \times 10} = 8 \times 10 \times 4 = 320[/tex]

[tex] \sqrt{7 \times 700} = \sqrt{49 \times 100} = 7 \times 10 = 70[/tex]

[tex] \sqrt{6.4 \times 0.9} = \sqrt{64 \times .09} = 8 \times 0.3 = 2.4[/tex]

[tex] \sqrt{ \frac{81}{100} } = \frac{9}{10} = 0.9[/tex]

[tex] \frac{ \sqrt{8} }{ \sqrt{50} } = \sqrt{ \frac{4}{25} } = \frac{2}{5} [/tex]

[tex] \frac{ \sqrt{112} }{ \sqrt{7} } = \sqrt{ \frac{112}{7} } = \sqrt{16} = 4[/tex]

2)

[tex] \sqrt{3} \sqrt{48} = \sqrt{3 \times 48} = \sqrt{144} = 12[/tex]

[tex] \sqrt{0.4} \sqrt{3.6} = \sqrt{4 \times 36 \times 0.01} = 2 \times 6 \times 0.1 = 1.2[/tex]

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

3)

[tex] \sqrt{(1.9 {)}^{2} } = 1.9[/tex]

[tex] \sqrt{( - 1.3 {)}^{2} } = 1.3[/tex]

[tex] \sqrt{ {2}^{8} } = {2}^{4} = 16[/tex]