Giúp mình bài 17 với ạ

$\text{Câu 17 :}$

$\text{a)}$

$\text{→ Ta có :}$

$\text{x² - 4x}$

$\text{= x( x - 4 )}$

$\text{b)}$

$\text{→ Ta có :}$

$\text{$\dfrac{x}{x + 2}$ + $\dfrac{2}{x + 2}$}$

$\text{= $\dfrac{x + 2}{x + 2}$}$

$\text{= 1}$

$\text{→ Ta có :}$

$\text{$\dfrac{x²}{x - 1}$ - $\dfrac{2x - 1}{x - 1}$}$

$\text{= $\dfrac{x² - 2x + 1}{x - 1}$}$

$\text{= $\dfrac{( x - 1 )²}{x - 1}$}$

$\text{= x - 1}$

$\text{→ Ta có :}$

$\text{$\dfrac{2x}{x + 2}$ . $\dfrac{( x + 2 )²}{x²}$}$

$\text{= $\dfrac{2x . ( x + 2 )²}{( x + 2 ) . x²}$}$

$\text{= $\dfrac{2( x + 2 )}{x}$ }$

5 sao nha