Evaluate:
`int_(-1)^(4)3dx`

Explanation

To evaluate the integral \( \int_{-1}^{4} 3 \, dx \), we will follow these steps:

### Step 1: Identify the integral
The integral we need to evaluate is:
\[ \int_{-1}^{4} 3 \, dx \]

### Step 2: Factor out the constant
Since \( 3 \) is a constant, we can factor it out of the integral:
\[ = 3 \int_{-1}^{4} dx \]

### Step 3: Evaluate the integral of \( dx \)
The integral of \( dx \) over the interval from \(-1\) to \(4\) is simply the length of the interval:
\[ \int_{-1}^{4} dx = x \bigg|_{-1}^{4} = 4 - (-1) = 4 + 1 = 5 \]

### Step 4: Multiply by the constant
Now we multiply the result of the integral by the constant we factored out:
\[ 3 \cdot 5 = 15 \]

### Final Result
Thus, the value of the integral \( \int_{-1}^{4} 3 \, dx \) is:
\[ \boxed{15} \]

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