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\(\dfrac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\sqrt{\dfrac{216}{3}}\)

\(=\dfrac{\sqrt{6}\left(\sqrt{2}-1\right)}{2\left(\sqrt{2}-1\right)}-\sqrt{72}\)

\(=\dfrac{\sqrt{6}}{2}-6\sqrt{2}=\dfrac{\sqrt{6}-12}{2}\)

Ta có: \(A=\left(\sqrt{6}+\sqrt{10}\right)\cdot\sqrt{4-\sqrt{15}}\)

\(=\left(\sqrt{5}+\sqrt{3}\right)\left(\sqrt{5}-\sqrt{3}\right)\)

=5-3=2

9 tháng 5 2022

\(B=\sqrt{9+4\sqrt{5}}+\sqrt{9-4\sqrt{5}}\)

\(B=\sqrt{\left(\sqrt{5}+2\right)^2}+\sqrt{\left(\sqrt{5}-2\right)^2}\)

\(B=\left|\sqrt{5}+2\right|+\left|\sqrt{5}-2\right|\)

\(B=\sqrt{5}+2+\sqrt{5}-2\)

\(B=2\sqrt{5}\)

 

9 tháng 5 2022

\(A=\left(\dfrac{2\sqrt{3}-\sqrt{6}}{\sqrt{8}-2}-\dfrac{\sqrt{216}}{3}\right).\dfrac{1}{\sqrt{6}}\)

\(A=\left(\dfrac{\sqrt{12}-\sqrt{6}}{2\sqrt{2}-2}-\dfrac{6\sqrt{6}}{3}\right).\dfrac{1}{\sqrt{6}}\)

\(A=\left(\dfrac{\sqrt{6}\left(\sqrt{2}-1\right)}{2\left(\sqrt{2}-1\right)}-2\sqrt{6}\right).\dfrac{1}{\sqrt{6}}\)

\(A=\left(\sqrt{6}-2\sqrt{6}\right).\dfrac{1}{\sqrt{6}}\)

\(A=-\sqrt{6}.\dfrac{1}{\sqrt{6}}\)

\(A=-1\)

 

 

20 tháng 9 2017

\(P=\dfrac{4\cdot36^4-2\cdot6^9}{2^{10}\cdot3^8+6^8\cdot20}\)

\(=\dfrac{4\cdot\left(2^2\cdot3^2\right)^4-2\cdot2^9\cdot3^9}{2^{10}\cdot3^8+2^8\cdot3^8\cdot2^2\cdot5}\)

\(=\dfrac{2^{10}\cdot3^8-2^{10}\cdot3^9}{2^{10}\cdot3^8+2^{10}\cdot3^8\cdot5}\)

\(=\dfrac{2^{10}\cdot3^8\left(1-3\right)}{2^{10}\cdot3^8\left(1+5\right)}=\dfrac{-2}{6}=-\dfrac{1}{3}\)

26 tháng 2 2021

`(3^9. 3^20. 2^8)/(3^24. 243. 2^6)`

`=(3^29. 2^8)/(3^24. 3^5. 2^6)`

`=(3^29. 2^8)/(3^29. 2^6)`

`=2^2=4`

NV
14 tháng 7 2021

\(\sqrt{8-4\sqrt{3}}=\sqrt{6-2.\sqrt{6}.\sqrt{2}+2}=\sqrt{\left(\sqrt{6}-\sqrt{2}\right)^2}=\left|\sqrt{6}-\sqrt{2}\right|=\sqrt{6}-\sqrt{2}\)

\(\sqrt{9-6\sqrt{2}}=\sqrt{6-2\sqrt{6}.\sqrt{3}+3}=\sqrt{\left(\sqrt{6}-\sqrt{3}\right)^2}=\left|\sqrt{6}-\sqrt{3}\right|=\sqrt{6}-\sqrt{3}\)

\(\sqrt{8-4\sqrt{3}}=\sqrt{6}-\sqrt{2}\)

\(\sqrt{9-6\sqrt{2}}=\sqrt{6}-\sqrt{3}\)

6 tháng 8 2021

sửa đề \(\dfrac{3x^2+6x+12}{x^3-8}=\dfrac{3\left(x^2+2x+4\right)}{\left(x-2\right)\left(x^2+2x+4\right)}=\dfrac{3}{x-2}\)ĐK : x \(\ne\) 2 

\(\dfrac{3x^2+6x+12}{x^3-8}=\dfrac{3\left(x^2+2x+4\right)}{\left(x-2\right)\left(x^2+2x+4\right)}=\dfrac{3}{x-2}\)