Question

Answer 1

Lời giải:

a. 

$P=\frac{(\sqrt{x}+1)^2-(\sqrt{x}-1)^2}{(\sqrt{x}-1)(\sqrt{x}+1)}.\frac{\sqrt{x}+1}{\sqrt{x}}$

$=\frac{4\sqrt{x}}{(\sqrt{x}-1)(\sqrt{x}+1)}.\frac{\sqrt{x}+1}{\sqrt{x}}$

$=\frac{4}{\sqrt{x}-1}$

b.

$P=2\Leftrightarrow \frac{4}{\sqrt{x}-1}=2$

$\Leftrightarrow \sqrt{x}-1=2$

$\Leftrightarrow \sqrt{x}=3$

$\Leftrightarrow x=9$ (tm)