Question

giúp em câu 18,19

Answer 1

Bài 12:

a: Ta có: \(P=\dfrac{x+2}{x\sqrt{x}-1}+\dfrac{\sqrt{x}+1}{x+\sqrt{x}+1}+\dfrac{1}{1-\sqrt{x}}\)

\(=\dfrac{x+2+x-1-x-\sqrt{x}-1}{\left(\sqrt{x}-1\right)\left(x+\sqrt{x}+1\right)}\)

\(=\dfrac{\sqrt{x}}{x+\sqrt{x}+1}\)

b: Thay \(x=28-6\sqrt{3}\) vào P, ta được:

\(P=\dfrac{5-\sqrt{3}}{28-6\sqrt{3}+5-\sqrt{3}+1}=\dfrac{5-\sqrt{3}}{34-7\sqrt{3}}=\dfrac{149+\sqrt{3}}{1009}\)