Cho các giới hạn: lim x → x 0 f ( x ) = 2 ; lim x → x 0 g ( x ) = 3 , hỏi lim x → x 0 [ 3 f ( x ) − 4 g ( x ) ] bằng bao nhiêu?

11/22

Cho các giới hạn: \(\mathop {\lim }\limits_{x \to {x_0}} f\left( x \right) = 2\); \(\mathop {\lim }\limits_{x \to {x_0}} g\left( x \right) = 3\), hỏi \(\mathop {\lim }\limits_{x \to {x_0}} \left[ {3f\left( x \right) - 4g\left( x \right)} \right]\) bằng bao nhiêu?

\(5\).

\(2\).

\( - 6\).

\(3\).

Giải thích

Đáp án đúng là: C

Ta có \(\mathop {\lim }\limits_{x \to {x_0}} \left[ {3f\left( x \right) - 4g\left( x \right)} \right]\)\( = \mathop {\lim }\limits_{x \to {x_0}} 3f\left( x \right) - \mathop {\lim }\limits_{x \to {x_0}} 4g\left( x \right)\)\( = 3\mathop {\lim }\limits_{x \to {x_0}} f\left( x \right) - 4\mathop {\lim }\limits_{x \to {x_0}} g\left( x \right)\)\( = - 6\).