Tính các giới hạn sau: a) \(\mathop {\lim }\limits_{x \to - 3} \left( {4{x^2} - 5x + 6} \right)\); b) \(\mathop {\lim }\limits_{x \to 2} \frac{{2{x^2} - 5x + 2}}\); c) \(\mathop {\lim }\limits_{x \to 4} \frac{{\sqrt x - 2}}{{{x^2} - 16}}\).

Tính các giới hạn sau:

a) \(\mathop {\lim }\limits_{x \to - 3} \left( {4{x^2} - 5x + 6} \right)\);

b) \(\mathop {\lim }\limits_{x \to 2} \frac{{2{x^2} - 5x + 2}}\);

c) \(\mathop {\lim }\limits_{x \to 4} \frac{{\sqrt x - 2}}{{{x^2} - 16}}\).