Tính giới hạn sau: Lim {\căn {2x + 3}  - 3/ - 3x + 9

\(\mathop {\lim }\limits_{x \to 3} \frac{{\sqrt {2x + 3} - 3}}{{ - 3x + 9}} = \mathop {\lim }\limits_{x \to 3} \frac{{(\sqrt {2x + 3} - 3)(\sqrt {2x + 3} + 3)}}{{( - 3x + 9)(\sqrt {2x + 3} + 3)}}\)

\(\begin{array}{l}\mathop { = \lim }\limits_{x \to 3} \frac{{2x - 6}}{{( - 3x + 9)(\sqrt {2x + 3} + 3)}} = \mathop {\lim }\limits_{x \to 3} \frac{{2(x - 3)}}{{ - 3(x - 3)(\sqrt {2x + 3} + 3)}}\\ = \mathop {\lim }\limits_{x \to 3} \frac{2}{{ - 3(\sqrt {2x + 3} + 3)}} = - \frac{1}{9}\end{array}\)