Đáp án:
$a)\quad \lim\dfrac{3n^3 + 2n^2 + n}{n^3 + 4}=3$
$b)\quad \lim\dfrac{4^n + 3}{2 - 2.4^n}=-\dfrac12$
Giải thích các bước giải:
$a)\quad \lim\dfrac{3n^3 + 2n^2 + n}{n^3 + 4}$
$=\lim\dfrac{3 + \dfrac2n + \dfrac{1}{n^2}}{1 +\dfrac{4}{n^3}}$
$=\dfrac{3+0+0}{1+0}$
$= 3$
$b)\quad \lim\dfrac{4^n + 3}{2 - 2.4^n}$
$=\lim\dfrac{1 + 3.\left(\dfrac14\right)^n}{2.\left(\dfrac14\right)^n - 2}$
$=\dfrac{1 + 3.0}{2.0 - 2}$
$= -\dfrac12$
