Question

Answer 1

Bài 12 :

a, Với x > 0 ; x khác 4 

\(A=\left(\dfrac{\sqrt{x}-4+3\sqrt{x}}{\sqrt{x}\left(\sqrt{x}-2\right)}\right):\left(\dfrac{x-4-x}{\sqrt{x}\left(\sqrt{x}-2\right)}\right)=\dfrac{4\sqrt{x}-4}{-4}=1-\sqrt{x}\)

b, Ta có \(\sqrt{x}=\sqrt{\left(\sqrt{5}-1\right)^2}=\sqrt{5}-1\)

\(A=1-\sqrt{5}-1=-\sqrt{5}\)