799 Вправа 799Алгебра 8 клас Бевз 2025 · § 16 · стор. 153

799. Виконай дії.

Розкриваємо дужки: ${\displaystyle \sqrt{a}\cdot \sqrt{b}=}$${\displaystyle \sqrt{ab}}$.

а) ${\displaystyle (\sqrt{12}+\sqrt{75})\cdot \sqrt{3}=}$${\displaystyle \sqrt{36}+\sqrt{225}}$=

=${\displaystyle 6+15=}$${\displaystyle 21}$;

б) ${\displaystyle (\sqrt{18}-\sqrt{50})\cdot \sqrt{2}=}$${\displaystyle \sqrt{36}-\sqrt{100}}$=

=${\displaystyle 6-10=}$${\displaystyle -4}$;

в) ${\displaystyle (4\sqrt{3}-\sqrt{27})\cdot \sqrt{12}=}$${\displaystyle (4\sqrt{3}-3\sqrt{3})\cdot 2\sqrt{3}}$=

=${\displaystyle \sqrt{3}\cdot 2\sqrt{3}=}$${\displaystyle 2\cdot 3=}$${\displaystyle 6}$;

г) ${\displaystyle (-3\sqrt{18}+\sqrt{72})\cdot 2\sqrt{2}}$=

=${\displaystyle (-9\sqrt{2}+6\sqrt{2})\cdot 2\sqrt{2}=}$${\displaystyle -3\sqrt{2}\cdot 2\sqrt{2}}$=

=${\displaystyle -6\cdot 2=}$${\displaystyle -12}$.