Evaluate : `int_(-1)^(2)e^(x) dx` as a limit of sum.

Explanation

To evaluate the integral \(\int_{-1}^{2} e^x \, dx\) as a limit of sums, we will follow these steps:

### Step 1: Define the integral as a limit of sums
The integral \(\int_{a}^{b} f(x) \, dx\) can be expressed as:
\[ \int_{a}^{b} f(x) \, dx = \lim_{n \to \infty} \sum_{i=0}^{n-1} f(a + i \cdot h) \cdot h \]
where \(h = \frac{b - a}{n}\).
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