Question

Tính. d/

Answer 1

`d)26/(2sqrt3+5)-4/(sqrt3-2)`

`=26/(5+2sqrt3)+4/(2-sqrt3)`

`=(26(5-2sqrt3))/(25-12)+(4(2+sqrt3))/(4-3)`

`=(26(5-2sqrt3))/13+(4(2+sqrt3))/1`

`=2(5-2sqrt3)+4(2+sqrt3)`

`=10-4sqrt3+8+4sqrt3=18`

Answer 2

Ta có : \(\dfrac{26}{2\sqrt{3}+5}-\dfrac{4}{\sqrt{3}-2}\)\(=\dfrac{26\left(\sqrt{3}-2\right)-4\left(2\sqrt{3}+5\right)}{\left(\sqrt{3}-2\right)\left(2\sqrt{3}+5\right)}\)

\(=\dfrac{26\sqrt{3}-52-8\sqrt{3}-20}{6-4\sqrt{3}+5\sqrt{3}-10}\) \(=\dfrac{18\sqrt{3}-72}{\sqrt{3}-4}=\dfrac{18\left(\sqrt{3}-4\right)}{\sqrt{3}-4}=18\)