Question

Giúp em với ạ(ghi đầy đủ ạ)

Answer 1

`D=(a+4sqrta+4)/(sqrta+2)+(4-a)/(sqrta-2)`

`=(sqrta+2)^2/(sqrta+2)+((2-sqrta)(2+sqrta))/(sqrta-2)`

`=sqrta+2-(2+sqrta)`

`=0`

Answer 2

ĐK: a ≥ 0; a khác 4

\(D=\dfrac{a+\sqrt{a}+4}{\sqrt{a}+2}+\dfrac{\left(2-\sqrt{a}\right)\left(2+\sqrt{a}\right)}{\sqrt{a}-2}\)

\(=\dfrac{a+\sqrt{a}+4}{\sqrt{a}+2}-\left(2+\sqrt{a}\right)\)

\(=\dfrac{\left(a+\sqrt{a}+4\right)-\left(2+\sqrt{a}\right)^2}{\sqrt{a}+2}=\dfrac{a+\sqrt{a}+4-\left(4+4\sqrt{a}+a\right)}{\sqrt{a}+2}=\dfrac{a+\sqrt{a}+4-4-4\sqrt{a}-a}{\sqrt{a}+2}=-\dfrac{3}{\sqrt{a}}\)