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

a/ \(0,1\sqrt{2.10000=0,1\sqrt{ }2.100^{ }2=0,1\cdot100\sqrt{ }2=10\sqrt{ }2}\) 

b/ \(-0,05\sqrt{28800}=-0,05\sqrt{288\cdot100=-0,05\cdot10\sqrt{ }288=6\sqrt{ }2}\) 

c/\(\sqrt{7\cdot63}a^2=\sqrt{7\cdot9\cdot7}a^2=21a^2\) 

\(\sqrt{72a^{ }2b\sqrt{ }4=\sqrt{ }6\cdot9\left|\right|ab^{ }2=-3\sqrt{ }6ab^{ }2}\)

\(\sqrt{72a^{ }2b^{ }4}=\sqrt{6.9}\left|ab^{ }2\right|=3\sqrt{6}-\left(ab^{ }2\right)=-3\sqrt{6}ab^2\) 

mk sữa lại câu d

a: \(=\sqrt{4\cdot a^4b^2\cdot7}=2a^2b\sqrt{7}\left(b>=0\right)\)

b: \(=\sqrt{36\cdot b^4\cdot a^2\cdot2}=-6ab^2\sqrt{2}\)

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) = \(4\sqrt{3}+3\sqrt{3}-3\sqrt{5}+\sqrt{5}=\sqrt{3}\cdot\left(4+3\right)-\sqrt{5}\cdot\left(3-1\right)=7\sqrt{3}-2\sqrt{5}\)

b) = \(2a^2b\sqrt{7b}\)

c) = \(6ab^2\sqrt{2}\)

a. \(4\sqrt{3}+\sqrt{27}-\sqrt{45}+\sqrt{5}=4\sqrt{3}+3\sqrt{3}-3\sqrt{5}+\sqrt{5}=\left(4+3\right)\sqrt{3}-\left(3-1\right)\sqrt{5}=7\sqrt{3}-2\sqrt{5}\)b. \(\sqrt{28a^4b^2}=2a^2b\sqrt{7}\)( vì b>=0)

c.\(\sqrt{72a^2b^4}=-6ab^2\sqrt{2}\)( vì a<o)

a: ĐKXĐ: 2x-10>=0

=>2x>=10

=>x>=5

b: \(\sqrt{A^2B}=\sqrt{A^2}\cdot\sqrt{B}=\left|A\right|\cdot\sqrt{B}\)

\(\sqrt{72}=\sqrt{36\cdot2}=6\sqrt{2}\)

c: \(A=\sqrt{16}+\sqrt{81}=4+9=13\)

\(B=\sqrt{\dfrac{\left(15\sqrt{5}+5\sqrt{200}-3\sqrt{450}\right)}{\sqrt{10}}}\)

\(=\sqrt{\dfrac{15}{\sqrt{2}}+5\sqrt{20}-3\sqrt{45}}\)

\(=\sqrt{\dfrac{15\sqrt{2}+2\sqrt{5}}{2}}=\sqrt{\dfrac{30\sqrt{2}+4\sqrt{5}}{4}}\)

\(=\dfrac{\sqrt{30\sqrt{2}+4\sqrt{5}}}{2}\)

\(C=\dfrac{3+2\sqrt{3}}{\sqrt{3}}+\dfrac{2+\sqrt{2}}{1+\sqrt{2}}-\left(2+\sqrt{3}\right)\)

\(=\dfrac{\sqrt{3}\left(2+\sqrt{3}\right)}{\sqrt{3}}-\left(2+\sqrt{3}\right)+\dfrac{\sqrt{2}\left(\sqrt{2}+1\right)}{\sqrt{2}+1}\)

\(=2+\sqrt{3}-2-\sqrt{3}+\sqrt{2}=\sqrt{2}\)

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

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

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

√(28a4b2 ) = √((2a2b)2.7) = √7 |2a2b| = 2√7a2b (do b ≥ 0)