@py
Bài làm :
Điều kiện : x $\neq$ 0; x $\neq$ ±3
Ta có :
P = $\dfrac{(a + 3)²}{2a² + 6a}$ . ( 1 - $\dfrac{6a - 18}{a² - 9}$ )
P = $\dfrac{(a + 3)² }{2a( a + 3 )}$ . ( 1 - $\dfrac{6(a - 3)}{(a - 3)(a + 3)}$ )
P = $\dfrac{a + 3}{2a}$ . ( 1 - $\dfrac{6}{a + 3}$ )
P = $\dfrac{a + 3}{2a}$ . $\dfrac{a - 3}{a + 3}$
P = $\dfrac{a - 3}{2a}$