Tính I – J.

A

\(I = \mathop {\lim }\limits_{x \to 0} \frac{{2\left( {\sqrt {3x + 1}  - 1} \right)}}{x}\)\( = \mathop {\lim }\limits_{x \to 0} \frac{{2.3x}}{{x\left( {\sqrt {3x + 1}  + 1} \right)}}\)\( = \mathop {\lim }\limits_{x \to 0} \frac{6}{{\sqrt {3x + 1}  + 1}} = 3\).

\(J = \mathop {\lim }\limits_{x \to  - 1} \frac{{{x^2} - x - 2}}{{x + 1}}\)\( = \mathop {\lim }\limits_{x \to  - 1} \frac{{\left( {x - 2} \right)\left( {x + 1} \right)}}{{x + 1}}\)\( = \mathop {\lim }\limits_{x \to  - 1} \left( {x - 2} \right) =  - 3\).

Do đó I – J = 6.