It seems like you're trying to write an integral expression. Based on the formatting, I'm interpreting your input as the integral of a function involving $x$ with respect to $x$. Here's how it might be written more formally:

$\int_{-1}^{3} f(x) \, dx$

However, you haven't specified the function $f(x)$. If the function you're referring to is just $x$, then the integral would be:

$\int_{-1}^{3} x \, dx$

Let's solve that integral:

1. Set up the integral: $\int_{-1}^{3} x \, dx$

2. Integrate the function: \frac{x^2}{2} \quad \text{(since the integral of x$is$\frac{x^2}{2})}

3. Evaluate the definite integral from $-1$ to $3$: [ \left[ \frac{x^2