\(1,\\ a,=6\sqrt{2}:2\sqrt{2}=3\\ b,=\left(2\sqrt{7}-\sqrt{7}+4\sqrt{7}\right):\sqrt{7}=5\sqrt{7}:\sqrt{7}=5\\ 2,\\ a,=\dfrac{7\sqrt{2}}{4}:\dfrac{5\sqrt{2}}{4}=\dfrac{7\sqrt{2}}{4}\cdot\dfrac{4}{5\sqrt{2}}=\dfrac{7}{5}\\ b,=\sqrt{\dfrac{54x}{6x}}=\sqrt{9}=3\\ c,=\dfrac{\sqrt{5}}{25}\cdot\dfrac{4\sqrt{70}}{35}:\dfrac{2\sqrt{14}}{5}=\dfrac{\sqrt{5}\cdot4\sqrt{70}\cdot5}{25\cdot5\cdot2\sqrt{14}}=\dfrac{100\sqrt{14}}{250\sqrt{14}}=\dfrac{2}{5}\)
Bài 4:
a: \(\dfrac{x^3}{y^2}:\sqrt{\dfrac{x^2}{y^4}}=\dfrac{x^3}{y^2}\cdot\dfrac{y^2}{x}=x^2\)
b: \(\sqrt{\dfrac{27\left(x-1\right)^2}{12}}+\dfrac{3}{2}-\left(x-2\right)\cdot\sqrt{\dfrac{50x^2}{8\left(x-2\right)^2}}\)
\(=\dfrac{3\left(x-1\right)+3}{2}-\left(x-2\right)\cdot\dfrac{-5x}{2\left(x-2\right)}\)
\(=\dfrac{3x}{2}+\dfrac{5x}{2}\)
=4x
\(3,\\ \sqrt{\dfrac{a-1}{a+2}}:\sqrt{\dfrac{a+2}{a^3-3a^2+3a-1}}=\dfrac{\sqrt{a-1}}{\sqrt{a+2}}\cdot\dfrac{\sqrt{\left(a-1\right)^3}}{\sqrt{a+2}}=\dfrac{\sqrt{\left(a-1\right)^4}}{\sqrt{\left(a+2\right)^2}}=\dfrac{\left(a-1\right)^2}{a+2}\)
