Ai làm nhanh đúng 5 soa và 1cảm ơn

Đáp án + Giải thích các bước giải:

ĐKXĐ: $x \ne \pm 3$

 a) $\frac{3 - 2x}{x^2 - 9} + \frac{1}{2x - 6}$
$= \frac{3 - 2x}{(x + 3)(x - 3)} + \frac{1}{2(x - 3)}$

$= \frac{2(3 - 2x)}{2(x + 3)(x - 3)} + \frac{(x + 3)}{2(x - 3)(x + 3)}$

$= \frac{6 - 4x + x + 3}{2(x + 3)(x - 3)}$

$= \frac{-3x + 9}{2(x + 3)(x - 3)}$

$= \frac{-3(x - 3)}{2(x + 3)(x - 3)}$
$= \frac{-3}{2(x + 3)}$

$= \frac{-3}{2x + 6}$

ĐKXĐ: $x \ne \pm 3$

b) $\frac{x^2 + 3x}{x^2 + 6x + 9} + \frac{3}{x - 3} + \frac{6x}{9 - x^2}$
$= \frac{x(x + 3)}{(x + 3)^2} + \frac{3}{x - 3} + \frac{-6x}{x^2 - 9}$
$= \frac{x}{x + 3} + \frac{3}{x - 3} + \frac{-6x}{(x + 3)(x - 3)}$

$= \frac{x(x - 3)}{(x + 3)(x - 3)} + \frac{3(x + 3)}{(x + 3)(x - 3)} + \frac{-6x}{(x + 3)(x - 3)}$

$= \frac{x^2 - 3x + 3x + 9 - 6x}{(x + 3)(x - 3)}$

$= \frac{x^2 - 6x + 9}{(x + 3)(x - 3)}$

$= \frac{(x - 3)^2}{(x + 3)(x - 3)}$

$= \frac{x - 3}{x + 3}$