Giải 5 câu cho mình nha.

Đáp án+Giải thích các bước giải:

 `A=2\sqrt{27/4}-\sqrt{48/9}-2/5\sqrt{75/16}`

`=\frac{2.\sqrt{27}}{\sqrt{4}}-\frac{\sqrt{48}}{\sqrt{9}}-2/5.\frac{\sqrt{75}}{\sqrt{16}}`

`=\frac{2.\sqrt{3^{2}.3}}{2}-\frac{\sqrt{4^{2}.3}}{3}-2/5.\frac{\sqrt{5^{2}.2}}{4}`

`=\frac{2.3\sqrt{3}}{2}-\frac{4\sqrt{3}}{3}-\frac{2.5\sqrt{2}}{5.2.2}`

`=\sqrt{3}.(6/2-4/3-1/2)`

`=\sqrt{3}.(5/2-4/3)`

`=\sqrt{3}.(15/6-8/6)`

`=\frac{7\sqrt{3}}{6}`

Vậy `A=\frac{7\sqrt{3}}{6}`

`b)`

`B=2\sqrt{9/8}-\sqrt{49/2}+\sqrt{25/18}`

`=2\frac{\sqrt{9}}{\sqrt{8}}-\frac{\sqrt{49}}{\sqrt{2}}+\frac{\sqrt{25}}{\sqrt{18}}`

`=\frac{2.3}{\sqrt{2^{2}.2}}-\frac{7}{\sqrt{2}}+\frac{5}{\sqrt{3^{2}.2}}`

`=\frac{2.3}{2\sqrt{2}}-\frac{7}{\sqrt{2}}+\frac{5}{3\sqrt{2}}`

`=\frac{3}{\sqrt{2}}-\frac{7}{\sqrt{2}}+\frac{5}{3\sqrt{2}}`

`=\frac{3.3-7.3+5}{3\sqrt{2}}`

`=\frac{-7}{3\sqrt{2}}`

`=\frac{-7.\sqrt{2}}{3.2}`

`=-\frac{7\sqrt{2}}{6}`

Vậy `B=-\frac{7\sqrt{2}}{6}`

`C=(\sqrt{8/3}-\sqrt{24}+\sqrt{50/3}).\sqrt{6}`

`=(\frac{\sqrt{2^{2}.2}}{\sqrt{3}}-\sqrt{2^{2}.6}+\frac{\sqrt{50}}{\sqrt{3}}).\sqrt{6}`

`=(\frac{2.\sqrt{2}.\sqrt{3}}{(\sqrt{3})^{2}}-2\sqrt{6}+\frac{\sqrt{5^{2}.2}}{\sqrt{3}}).\sqrt{6}`

`=(\frac{2\sqrt{6}}{3}-2\sqrt{6}+\frac{5\sqrt{2}.\sqrt{3}}{(\sqrt{3})^{2}).\sqrt{6}`

`=(\frac{2\sqrt{6}}{3}-2\sqrt{6}+\frac{5\sqrt{6}}{3}).\sqrt{6}`

`=\sqrt{6}.\sqrt{6}.(2/3-2+5/3)`

`=\sqrt{6^{2}}.(7/3-2)`

`=6.(7/3-6/3)`

`=6. 1/3`

`=6/3`

`=2`

Vậy `C=2`

`D=\sqrt{1/8}.\sqrt{2}.\sqrt{125}.\sqrt{1/5}`

`=\sqrt{1/8. 2. 125. 1/5}`

`=\sqrt{1/40.250}`

`=\sqrt{\frac{250}{40}}`

`=\sqrt{25/4}`

`=\sqrt{(5/2)^{2}}`

`=|5/2|`

`=5/2`

Vậy `D=5/2`

`E=(1/2 \sqrt{1/2}-3/2\sqrt{4,5}+2/5\sqrt{50}):4/5\sqrt{1/8}`

`=(1/2.\frac{1}{\sqrt{2}}-3/2.\frac{3\sqrt{2}}{2}+2/5.\sqrt{5^{2}.2}):(4/5.\frac{1}{\sqrt{8}})`

`=(\frac{1}{2\sqrt{2}}-\frac{3.3\sqrt{2}}{2.2}+2/5. 5\sqrt{2}):(\frac{4.1}{5.2\sqrt{2}})`

`=(\frac{1}{2\sqrt{2}}-\frac{9\sqrt{2}}{4}+2\sqrt{2}):\frac{2}{5\sqrt{2}}`

`=(\frac{1}{2\sqrt{2}}:\frac{2}{5\sqrt{2}})-(\frac{9\sqrt{2}}{4}:\frac{2}{5\sqrt[2}})+(2\sqrt{2}:\frac{2}{5\sqrt{2}})`

`=5/4-45/4+10`

`=-40/4+10`

`=-10+10`

`=0`

Vậy `E=0`