Question

Rút gọn biểu thức:

Answer 1

\(=\dfrac{\left(\sqrt{a}+2\right)^2}{\sqrt{a}+2}-\dfrac{\left(\sqrt{a}-2\right)\left(\sqrt{a}+2\right)}{\sqrt{a}-2}\\ =\sqrt{a}+2-\sqrt{a}-2=0\)

Answer 2