Tính giới hạn lim x → 0 4 x 3 − √ 9 + x .

\(\mathop {\lim }\limits_{x \to 0} \frac{{4x}}{{3 - \sqrt {9 + x} }}\)\( = \mathop {\lim }\limits_{x \to 0} \frac{{4x\left( {3 + \sqrt {9 + x} } \right)}}{{9 - \left( {9 + x} \right)}}\)\( = \mathop {\lim }\limits_{x \to 0} \left[ { - 4\left( {3 + \sqrt {9 + x} } \right)} \right] = - 24\).

Trả lời: −24.