Вопрос
lim _(xarrow infty )((2x-3)/(2x+1))^5x
Решения
4.6
(234 Голоса)
Тимон
Экспертная проверка
мастер · Репетитор 5 лет
Ответ
To evaluate the limit \(\lim_{x \to \infty} \left(\frac{2x-3}{2x+1}\right)^{5x}\), we can use the following steps:1. **Simplify the expression inside the limit:**
As
, the terms
and
approach 0. Therefore, the expression simplifies to:
2. **Rewrite the limit in terms of the simplified expression:**
3. **Use the approximation
as
:**
4. **Simplify the exponent:**
5. **Evaluate the limit of each part separately:** - The term
grows exponentially as
. - The term \((2x+1)^{-5x}\) can be analyzed using Stirling's approximation or the properties of exponential functions. Specifically, \((2x+1)^{-5x}\) behaves like \((2x)^{-5x}\) for large
:
As
, \(\ln(2x) \approx x \ln(2)\), so:
Therefore,
6. **Combine the results:** Since
grows exponentially and \((2x+1)^{-5x}\) decays exponentially, the overall expression tends to:
Thus, the limit is: