Tìm giới hạn B= lim x^4 - 5x^2 + 4/ x^3 - 8

Ta có \(B = \mathop {\lim }\limits_{x \to 2} \frac{{{x^4} - 5{x^2} + 4}}{{{x^3} - 8}} = \mathop {\lim }\limits_{x \to 2} \frac{{\left( {{x^2} - 1} \right)\left( {{x^2} - 4} \right)}}{{{x^3} - {2^3}}}\)

\[ = \mathop {\lim }\limits_{x \to 2} \frac{{\left( {{x^2} - 1} \right)\left( {x - 2} \right)\left( {x + 2} \right)}}{{\left( {x - 2} \right)\left( {{x^2} + 2x + 4} \right)}}\]\( = \mathop {\lim }\limits_{x \to 2} \frac{{\left( {{x^2} - 1} \right)\left( {x + 2} \right)}}{{{x^2} + 2x + 4}} = 1.\)

Đáp án: 1.