Nếu sai mong bạn thông cảm:

\(\sqrt{50.6}=\sqrt{300}=\sqrt{2^2.5^2.3}=2.5\sqrt{3}=10\sqrt{3}\)

\(\sqrt{50\cdot6}=\sqrt{300}=10\sqrt{3}\)

a )\(x\sqrt{7}\)

b )\(-2y\sqrt{2}\)

c )\(5x\sqrt{x}\)

d)\(4y^2\sqrt{3}\)

a: \(\sqrt{5a^2}=\left|a\sqrt{5}\right|=-a\sqrt{5}\left(a< =0\right)\)

c: A=\(\sqrt{72a^2b^4}=\sqrt{36a^2b^4\cdot2}=6\sqrt{2}\cdot b^2\cdot\left|a\right|\)

mà a<0

nên \(A=-6\sqrt{2}\cdot ab^2\)

d: \(\sqrt{24a^4b^8}=\sqrt{4a^4b^8\cdot6}=2a^2b^4\cdot\sqrt{6}\)

\(a,=6\left|a\right|b^2\sqrt{2}=6ab^2\sqrt{2}\\ b,=3\left|ab\right|\sqrt{3a}=-3ab\sqrt{3a}\)

\(\sqrt{\left(-9\right)\cdot\left(-36\right)\cdot ab^2}\)

\(=\sqrt{9\cdot36\cdot ab^2}\)

\(=3\cdot4\cdot\left|b\right|\cdot\sqrt{a}\)

\(=12\left|b\right|\cdot\sqrt{a}\)

8 y 2 = 4 . 2 y 2 = 2 y 2 = - 2 y 2 ( với y < 0 )

\(\sqrt{48\cdot45}=12\sqrt{15}\\ \sqrt{225\cdot17}=15\sqrt{17}\\ \sqrt{a^3b^7}=\left|ab^3\right|\sqrt{ab}=ab^3\sqrt{ab}\\ \sqrt{x^5\left(x-3\right)^2}=\left|x^2\left(x-3\right)\right|\sqrt{x}=x^2\left(x-3\right)\sqrt{x}\)

\(\sqrt{48\cdot45}=4\sqrt{3}\cdot3\sqrt{5}=12\sqrt{15}\)

\(\sqrt{225\cdot17}=15\sqrt{17}\)

b)  63 y 3 7 y với y > 0

=  63 y 3 7 y = 9 y 2 = 3 y = 3 y do y > 0

\(\sqrt{x^3-6x^2+12x-8}\)

\(=\sqrt{\left(x-2\right)^3}\)

\(=\left|x-2\right|\cdot\sqrt{x-2}\)

25 x 3 = 25 x 2 . x = 5 x x = 5 x x ( với x > 0 )