We need to find the limit of the function $\frac{e^x + 2x - 1}{2e^x + 1}$ as $x$ approaches infinity.
2025/4/26
1. Problem Description
We need to find the limit of the function as approaches infinity.
2. Solution Steps
We are given the limit:
\lim_{x \to \infty} \frac{e^x + 2x - 1}{2e^x + 1}
As approaches infinity, also approaches infinity. Both the numerator and denominator approach infinity, so we have an indeterminate form of type . We can apply L'Hopital's Rule. L'Hopital's Rule states that if is of the form or , then , provided the limit on the right exists.
First, we find the derivatives of the numerator and the denominator:
\frac{d}{dx}(e^x + 2x - 1) = e^x + 2
\frac{d}{dx}(2e^x + 1) = 2e^x
So, applying L'Hopital's Rule once, we get:
\lim_{x \to \infty} \frac{e^x + 2x - 1}{2e^x + 1} = \lim_{x \to \infty} \frac{e^x + 2}{2e^x}
This is still of the form , so we can apply L'Hopital's Rule again.
\frac{d}{dx}(e^x + 2) = e^x
\frac{d}{dx}(2e^x) = 2e^x
So, applying L'Hopital's Rule a second time, we get:
\lim_{x \to \infty} \frac{e^x + 2}{2e^x} = \lim_{x \to \infty} \frac{e^x}{2e^x}
We can simplify the fraction:
\lim_{x \to \infty} \frac{e^x}{2e^x} = \lim_{x \to \infty} \frac{1}{2} = \frac{1}{2}
Alternatively, we can divide the numerator and denominator by from the beginning:
\lim_{x \to \infty} \frac{e^x + 2x - 1}{2e^x + 1} = \lim_{x \to \infty} \frac{1 + \frac{2x}{e^x} - \frac{1}{e^x}}{2 + \frac{1}{e^x}}
As , . Also, by L'Hopital's Rule (since ).
\lim_{x \to \infty} \frac{1 + \frac{2x}{e^x} - \frac{1}{e^x}}{2 + \frac{1}{e^x}} = \frac{1 + 0 - 0}{2 + 0} = \frac{1}{2}