385. Найдите значение произведения: a) $$\sqrt{2} \cdot \sqrt{8}$$; b) $$\sqrt{27} \cdot \sqrt{3}$$; v) $$\sqrt{28} \cdot \sqrt{7}$$; g) $$\sqrt{2} \cdot \sqrt{32}$$; d) $$\sqrt{13} \cdot \sqrt{52}$$; e) $$\sqrt{63} \cdot \sqrt{7}$$; z) $$\sqrt{50} \cdot \sqrt{4,5}$$; z) $$1,2 \cdot \sqrt{3\frac{1}{3}}$$.

a) $$\sqrt{2} \cdot \sqrt{8} = \sqrt{2 \cdot 8} = \sqrt{16} = 4$$

b) $$\sqrt{27} \cdot \sqrt{3} = \sqrt{27 \cdot 3} = \sqrt{81} = 9$$

v) $$\sqrt{28} \cdot \sqrt{7} = \sqrt{28 \cdot 7} = \sqrt{4 \cdot 7 \cdot 7} = \sqrt{4 \cdot 49} = 2 \cdot 7 = 14$$

g) $$\sqrt{2} \cdot \sqrt{32} = \sqrt{2 \cdot 32} = \sqrt{64} = 8$$

d) $$\sqrt{13} \cdot \sqrt{52} = \sqrt{13 \cdot 52} = \sqrt{13 \cdot 4 \cdot 13} = \sqrt{4 \cdot 13^2} = 2 \cdot 13 = 26$$

e) $$\sqrt{63} \cdot \sqrt{7} = \sqrt{63 \cdot 7} = \sqrt{9 \cdot 7 \cdot 7} = \sqrt{9 \cdot 49} = 3 \cdot 7 = 21$$

z) $$\sqrt{50} \cdot \sqrt{4,5} = \sqrt{50 \cdot 4,5} = \sqrt{225} = 15$$

z) $$1,2 \cdot \sqrt{3\frac{1}{3}} = 1,2 \cdot \sqrt{\frac{10}{3}} = \frac{12}{10} \cdot \sqrt{\frac{10}{3}} = \frac{6}{5} \cdot \sqrt{\frac{10}{3}} = \frac{6}{5} \cdot \frac{\sqrt{10}}{\sqrt{3}} = \frac{6}{5} \cdot \frac{\sqrt{10} \cdot \sqrt{3}}{3} = \frac{6}{5} \cdot \frac{\sqrt{30}}{3} = \frac{2}{5} \sqrt{30}$$

Ответы:

• a) 4


• b) 9


• v) 14


• g) 8


• d) 26


• e) 21


• z) 15


• z) $$\frac{2}{5} \sqrt{30}$$